Shacky, seriously man, why are those old b1 links STILL there

Did a run-through of your map.
The Vents:
Glad to see you can't access them from MS anymore. But they still seem excessive. The two marine-access parts have ladders, but are weldable. And then, marines can only go from the one marine-access to the other one. I'd suggest either
(1) removing marine access to both by placing them higher up, or
(2) removing the weldables (since welding one would ruin the other, but only after a marine spent 5 mins looking for an exit). If you removed the weldables, hence choosing to let the marines actively use the vents, i'd suggest giving them more options. Add more ladders to the vents so marines can ninja through them in certain areas.
Careful about the vents too; it seems like theres some really long parts. This can be useful for skulks, but you might want to give them an extra exit option now and then. But the real problem is marines. If a marine gets in the vents and goes a certain way, there should be an exit. If he goes all that way (like towards MS) and there isnt an exit, he will hate you. Either block the marine's access right away (height change etc), or give marine access to the exits further along.
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Nodes:
12 is just too many. Right now, your layout is very much like an upside-down Veil, except that you have a node at both System Waypointing and Dome (which are Fuel Feed and Pumping Station, in your map). I highly suggest lowering this to 10 nodes, which is the general standard of NS.
My suggestions for doing so:
(1) integrate Sewage and Electric Annex into one node, somewhere in between the two
(2) remove Fuel Feed node (very close to that hive, practically creates a second Double)
(3) turning Double into a single node, removing both Fuel and Pumping, and placing a new node at Data Bank
Those suggestions intertwine, but give you a lot of options for how you can lower the nodecount of your map.
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Careful with your
entity count. Turn on dev move (dev 1 in console), and type 'numents'. Beta 2 is at 248, which is getting high. Its still acceptable, but lower it if you can, and really try not to add any more for beta3. I noticed you have a TON of sprites throughout the map; they're a nice ambient effect, but they alone probably added about 40 runtime entities.
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Tram Hive. The infestation is WAY too much. There are parts where you can't see anything a foot in front of you. The skinny strand of infestation is a very nice touch, but the two thick pieces almost ruin the hive. You put the thickest parts at the floor and the thinnest at the ceiling; if inverted, this could help the problem. But i'd suggest lowering the scale on the textures (so the big blobs are that much smaller), and moving them about so that there's more visibility. A lot more visibility.
I find the infestation that cuts into the hive to be an odd effect as well. Perhaps try two or even three brushes instead of one? So that the infestation either comes around the hive like < (from two) or like \_/ (from 3)? That could solve that issue.
The
vent to the north of Tram isn't well placed, imo. Its a cool little effect you're trying to make, the skulks running under the feet of the marines, but it doesn't work out in many places. The transparent texture covers up too much visibility, and a marine would practically never notice a skulk running underneath. This vent in particular takes way too big of a detour just for this effect; you could shorten the vent up a lot by removing this under-area, or also by moving the vent entrances. I like the Pumping entrance, but its not very useful for where it ends up. Perhaps add another exit to the siege room southeast of tram hive?
The
vent to the east of Tram is ill-suited for marine accessibility, imo. You have the two entrances low to the ground (so marines can access them), and with ladders, but there would rarely be a situation where using these vents would be beneficial to the marines. Adventurous marines everywhere will hop into the vents, but almost certainly be very disappointed with the resulting exit. I'd suggest to either remove marine accessibility, or give more in-vent access to other parts of the map (perhaps cutting off marine access to the one close to the hive while you're at it). Your choice though.
Siegeing Tram Hive. From the east, you can hit the hive from the far-west side of Fuel Feeding; this is about 4 rooms away from the hive. Aliens would have a
very difficult time defending against such a siege.
From the west side, marines would have to be in the room adjacent to the hive room, with very little cover. I'd picture this as a semi-balanced siege, but if there was a single decent fade and the hive was built (regardless of another hive being built), I couldn't foresee aliens losing this fight.
My suggestion would be to move the hive more into the center of the hive room its in. That would roughly alleviate the problems found in siegeing from both sides.
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Freight elevator is a pretty cool room, good job. I'm having some issues with the elevator though, and also having problems figuring out exactly what the problem is. First off, I noticed that pressing a button disables it for quite some time, and that the elevator returns to its top position. But i noticed that pressing one button does not disable the other, leaving the elevator wide open to bugs.
The issue I had was from using only the bottom button. I'm not sure how it happened, but it happened a few times, where the elevator actually stuck to the bottom area for quite some time. I just played with it a bit, and i could only recreate it by going from the top (hitting the button), to the bottom, and then hitting the button at the bottom. A player would likely do this thinking that he's sending the elevator back up. Hence, you could fix this issue by either making both buttons disable together, or by removing the auto-return feature.
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In Steam Tunnel, those side pipes would be a lot cooler if a skulk could run up behind them

. I was disappointed in a live game on Forgotten once because of this. Your choice though.
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Drill Shaft Hive.Again, too heavy with the infestation. One entrance door is blocked almost 50% on the ground, which would infuriate most players on both sides. Ease up on that stuff. Also, the mixture of infestation gunk as well as infestation textures on the floors and walls creates a very highly camouflaging area for aliens. Its one thing for aliens to blend in, its quite another for them to be extremely hard to see. I'd suggest to tone that down a bit.
The
vent exit on the west side of the hive, again, takes the longest route ever to get to where its going. Yes the skulks pass under the floor of walking marines, but the effect is not worth the player irritation. I'd suggest to either change the vents so the runtime is quicker, or simply straighten them and avoid the underpass areas.
Siegeing Drill Shaft Hive:
This hive seems VERY problematic to siege. Its basically impossible from the north, without being actually in the hive room. And from the West, the sieges would have to be in the hall that has direct sieg into the hive room. Furthermore, I tried placing sieges down the hallway to the left, in Steam Tunnel, but no TFs would drop. Seems its either bugged or you placed func_nobuilds. Either way, it needs to be fixed.
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The
vents to the east of Electric Annex. Again with the extreme route for minimal effect. This is becoming a bit of a broken record with this map

. The vent, instead of taking 5 turns to go from the first room to Electric Annex, could instead take just one turn. Its marine-accessible from one side, but i really don't know why. I'd suggest making both entrances not marine-accessible, and doing the just-one-turn vent. Same concept, much higher efficiency, but you lose the visual effect that noone would ever have seen anyways.
But, if you're really set on keeping that visual effect (skulks running under marines), maybe you can highlight it somehow. Perhaps putting a bright texture under the skulks feet. It would likely brighten the marines as well (which could be bad), but at least it would make the skulk underneath far more visible. I'd suggest against it though.
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Sewer Hive.
Again. PLEASE cut down the infestation. There is so much that even playing alone, its annoying me. I couldn't imagine how irritated i'd be as either side actually having to fight in that. Noone likes to be blinded.
The water outside the hive might be a bit much too. Its just a tad too long for either side to be able to use it to their advantage; it would basically become a 'no mans land' in a normal game.
The weldable seems to take a very long time. Given what it does, I guess thats ok, but I'd consider revising this whole area. Without welding, theres no way marines can siege whatsoever from the south, and they cant even get a phasegate anywhere nearby.
And then, when marines DO weld, it becomes too easy for them. You can fit four sieges to hit the hive. Or, you can place sieges down in that turbine room, and aliens would be completely screwed. Also, the turbines seem a bit heavy on the damage; one just nicks a marines head even slightly and hes dead.
Furthermore, this hive can be sieged from right beside Pumping Station Node, which is
DEFINITELY too far. This whole area will likely need to be reworked, or the hive moved, or the entrances to the hive moved.
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The runtime to the middle hive is very high. At best its 40 seconds, which is the same as the worst middle hive runtime for the official maps (Fusion on Tanith). The other main route clocked 50 seconds. Drill hive has a fine runtime, and Sewer's was a bit higher than normal.
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Overview:
-Too many nodes, try to drop at least one, if not 2
-The siege areas are in very rough shape and need a lot of fixing
-the vents need to be made more efficient, and more consideration needs to be put into marine accessibility and their experiences (which would all be negative right now)
-the infestation in the hives needs to be toned down significantly
You have a great map, but it has a few pretty serious problems. If you can fix up these issues, you'd have a stellar map on your hands. Your brushwork and use of effects has come a long way, especially your proportions (ns_bliss was notorious for over-sized rooms

). Keep up the work and lets get this map into the map pack!
-Stix