I've been testing them out on blight for a while now, and I have to say these things are awesome. The art is great, they are absolutly beautiful. I love the lighting effects in the essense room. Planning them out is a lot of fun, my only gripe being that if you want to go back and change one section a little bit, you have to first delete everything that is attached to it. The maze of tunnles makes builiding your lair feel like it is truely yours and unique. And you gave a good ammount of room inside them, I belive. Using just 45% of my lair space (on a 120x120x144), I was able to place a shrine, two tier 4 libraries (I'd build them for the look, if nothing else :)) a tier 4 essense room, a tier 4 smelting room, a tier 3 (I think) Stoneworking room, a tier 5 lair, 1 tier 4 silo, 2 tier 3 silos, 1 tier 2 silo, and 4 tier 1 silos.
The only thing I would like to see added, and it is probibly too late for this, is some "mirrored" rooms. They would be the same as their existing counterparts, but reversed so that the attach points would line up diferently. That, and also some spiral down ramps that would change the exit direction, instead of going in a straight line from where you entered.
All in all, excelent work, you are going to keep me busy for a week of playtime just designing the thing.