I like this map. Very nice use of verticality, good texturing and detailing and a cool layout. I especially like the curved-rising hallway, the curved stairs, and some of the pipework/patchwork. Lighting seems good too. Bright enough to not make people whine, but still with some decent shadows and contrast.
Suggestions/Observations:
1) I'm a little hesitant about having a direct (via tele) connection from RA<-->RG. I'd maybe change one/both of the dests and/or remove one. Two-way teles are almost always less interesting and not as good for gameplay, IMO. Also,
2) I'd consider making RA a *bit* more dangerous to get--maybe remove one tele (the one to RG?) and/or remove some of the slope-jumpy trim so that it's not entirely along that whole side of the room, but only in a couple of spots? Hell, I'd be tempted to move the RA over where the +5s are by the pit o' lava-y death, but I'm a jerk that way; your milage may vary.
3) There are a few places where you just have a sort of stunted ramp up to change elevation rather than a few stairs. This seems weird to me...unfinished or something.
4) The stuff on the window ledges near DMG seems sort of annoying to pick up...
5) I'd consider moving the MH back a bit more since you have room there, or making it somehow a bit harder to get. I know that you have to slopejump if you're coming from the floor, but it's easy enough to hop over from the one hallway...
6) The rocks outside the windows in various places are a cool start, but I think you could make them more interesting...maybe a second "layer" a bit farther back for a bit more depth/parallax?
7) There's some fog weirdness going on under the Quad (DM) tele down by the lava...
Just for a final wacky idea to consider, I think it might be interesting to make a (dangerous and/or difficult...probably both) connection of some kind between the two lava areas, probably down closer to the lava...they're close enough, and I think you could maybe do it without hosing your portaling...
This is coming along very nicely.
(What happened to Dark Ritual?)
I beat the internet; the end guy is hard.