Also while I'm here, my one beef with GH2 was that every dungeon had no atmosphere, and as a result any armor that wasn't a space suit had no use, it bugged the hell out of me; does that lessen later on/is there a way around it later on?
There's actually a handful of GH2 dungeon areas with air (particularly notable are fungal infections, which are decent dosh), but no, most of them are sans-atmosphere. You are kinda' in space, heh. Most of the better armor in the game is sealed, though, and if you really don't like it you can mod in stuff to get around it pretty easily.
Oh, so space suits do eventually get better? Okay. In my attempts I only saw terrible suits and really good armor that... wouldn't let you breath, that's okay then. I'll have to give it another shot. I did like it quite a bit more then GH1 despite a few niggling things like that!
For sure in the later game it gets really hard to hit with non-thrown weapons, even extendable ones, because it pays to keep your mech moving pretty fast, and the enemies move at a pretty decent clip too. And it's possible to stuff in a LOT of thrusters and really zip around - add on stuff like "Born to Fly" for more bonuses 
I don't remember if "Stunt Driving" applied while flying, I'm pretty sure it did while hovering though, and it's relatively easy to pile on enough Arc Thrusters to hover pretty dang fast...
Same is true for almost the entirety of GH2. Since most fights occur in space, most fights occur under flying conditions. Go ranged or go home. I'd suggest at least one energy weapon so you can still fight at range after your ammo runs out. It's possible to keep firing energy weapons without power, they just don't do as much damage.
Weapon configurations vary drastically between GH1 and GH2. In GH1, the player gets to act whenever they move, so faster mechas get a lot of attacks, thus you generally want as many weapons as possible. In GH2, proper initiative rules (you only get to act when you get initiative) plus a much stricter mecha weight system means that it is generally better to have a small number of exceptional weapons.
It's also a lot easier to add a high-end targeting computer in GH1 than in GH2. In GH1, you just buy a Targeting Computer 10, strap it on your mecha, and you can load yourself down with tons of weapons and not suffer a minus to accuracy (because the Targeting Computer 10 reduces your penalty to hit due to mecha encumbrance by 10). In GH2, targeting software has to be loaded into computers at 50 memory per penalty reduction. Since the highest commercially-available computer has 200 memory, the best targeting computer you can buy is 200/50 = 4 reduction in penalty. I'm sure better computers are available on mecha, but it's gonna take a while to get those computers, and I believe the best computer is still less than the GH1 computer. I don't think it's possible to combine computers, but I'll check.
I always thought a good way to get around the "always moving since you're in space = melee sucks" would be to add a damage boost depending on how fast you're moving for melee. As I recall he's recoding Gearhead 2 anyway, or was, so maybe that's one of the reasons, I kind've forget why he started doing that.
