Hmm, it's not specifically part-related, but I do think the attack values for enemies, at least on Expert, could have the growth rate upped a bit further. Enemies that should probably be dealing decent damage like the limited-ammo sniper types dont do much even after a few levelups. In some cases it might be that the base attack power is too low. I havent messed with the new difficulty enough yet to judge it on that one, but it's likely that I'll find the same problem there as I go through it. I'd like to finish my current playthrough first though.
Also, regen, it seems like it's pretty hard for enemy shots to turn regen-able damage into permanent damage. I think that's part of why my AssaultExo is nigh invulnerable to anything but heavy attacks (like, at least a couple hundred damage at a time). That mechanic overall is working nicely, but that's my one issue with it right now. EDIT: Not just that though, but enemy attack values arent keeping up well with the rate at which shield values provided by items are going up. Heck, I've got both a capacitor and a shield item that are providing over 100 shields available in the store, both are blue items. For how far I am in this playthrough, and where the enemy attacks are currently (even among things that are gaining enough levelups) that's definitely a bit much.
EDIT: Ok, the bit with the enemy bots, seeing it go further, the problem seems like the bots that have low attack to start with, say 30 or so, they almost dont grow in attack power whatsoever as the game goes on. Bots that started out with decent attack are getting stronger properly, but for the ones that started low.... well, it leads to things like snipers that do no damage, and stuff like that. Heck, I've had a few missions that were mostly enemies of that type, where pretty much the entire bot population for the mission could barely even scratch my science exo.
I'll stick with the points I mentioned about the shield items and regen though.
Good grief though, so many numbers.... I dunno how you manage to balance things out in the first place.