Hiya, been playing tremulous a bit since the last release, been enjoying it quite a bit. There are a few little things which would make things more interesting (from my personal perspective) while playing from either the alien or marine side of things, that I wanted to share with any interested parties here. I tried to find a thread containing the same content via search and some browsing, but didn't come across one, apologies if one exists already.
From my perspective, humans across the board are just a little too quick and maneuverable. I haven't pulled down the source and checked hard figures (been meaning to, haven't got around to it yet sorry), but considering that (especially early game) aliens are relying 100% on melee attacks for combat action, it just doesn't quite feel balanced. Wallwalking is great for evading and dodging attacks, but in many situations it is no substitute for raw speed, and it seems all too easy for marines to hunt down fleeing aliens. Beeing able to shoot aliens as they try to run away at short distances is fine, being able to chase aliens down in a speed match around corners, through doors and corridors etc feels kinda weird. A slight speed decrease for marines (say 10%? even 5%?) and a slight increase of the same amount for aliens would balance things nicely, without nerfing or boosting either side to such an extent that it would cause grief to fans of the current stats.
The speed issue is compounded somewhat by the fact that all aliens have very visible skin coloration, and marines generally blend in slightly better with their surroundings. Every alien (except possibly the granger) shows up very easily against most wall textures, and aliens have quite wide models that don't seem to line up with the player view camera; this can make hiding behind obstructions or stealth tactics very difficult because you can't be sure if a large and obvious body part might not be sticking out and giving you away over a large distance. This mainly affects basilisks and dretches because of their low health and (relatively) weak melee capabilities.
An alien that had some kind of weak ranged attack early in the game would make an interesting change in the psychology of the average human player; if a small, quick and relatively hard to notice alien managed to get to a place within the human base they could harry human structures or create holes in the defence that would cause human players to be more base conscientious, and make base defense/maintenance more intense and fun. They could also offer dretches some much needed support against roving teams of humans, and provide a simple counter to jetpackers hovering in the middle of wide open spaces, since jetpacks cut out when their user takes damage.
Also, any chance grangers could get the ability to climb ladders (pre s2)? sucks when you fall down a hole and have to evolve to a dretch to get out

Oh, and for humans, is there any chance they might be able to one day trade in their blasters, pay some credits and trade in for a high power short clip pistol? Pistols are always fun :|
On a final note, any time I mention balance in the above paragraphs, it's when the two players fighting are of approximately equal skill level. The contents of this post are based on my experiences playing on both sides, and from carefully observing other players as well.