There's a bug in the Talay map in the small area with the vegetation (before you get into the Rebel Base proper you can see some textures floating in mid air (off to the right as you enter). There seems to be single lines hovering above the foliage.
Other than that, the outdoor areas really take a heavy hit in the FPS. I don't know what kind of machines y'all are using, but on mine I can't get more than 20-25 FPS in outdoor areas (secbase and talay) and in lots of places the FPS goes down even more (around 5 FPS or so)--especially when enemies are onscreen.
The other thing is that the enemy AI seems to be really dumb. Most of the time I could walk right up to enemies and they would just sit there as if I weren't there (makes it nice and easy to blow them away with a quick squeeze on the ST rifle trigger), and the ones that did
notice me would simply stay put and fire from the same location making it easy to run around them and burn them to a fine charred powder.
Also, the sound seems to snap, crackle and pop all the time, and this is with EAX turned off. I looked at your sounds and they seemed OK--it could be that they're recorded too hot. The other thing I've noticed is that the engine is very picky about the MP3s it'll play--that might be a factor as well.
Other than that, I'm impressed with what you guys have come up with. I can't improve on what others have already said about the look of the maps, so suffice it to say that I'm looking forward to seeing more.