#1: Right, point taken.
#2: I don't think that's a bad tradeoff, especially considering that the clockwork Craft (mechcraft) DC is so much higher than a steam-powered mech. As for smoke . . . it really depends how deep you're planning to delve in this thing.
#3: Yeah, but if the mech fails a save for something really nasty, then it's really, really nasty. Not just the high-level stuff like disintegrate
, but spells like gearghoul touch
as well. Maybe I'm just being paranoid on behalf of my eventual PCs.
#4: Okay, I can see that. It may get you into problems that you wouldn't have faced in normal armor, though.
#5: Two feats? Armor Proficiency (hydraulic) is a standalone feat. I agree that wasting a feat isn't good, but if you're a human (which most mech jockeys are), then you've got one extra feat, a front-loaded one you can't use later. Best to spend it on something useful.
#6: Not needing Combine Spell is good, but magic items are usually sized for Medium creatures. Things like a gauntlet of rust
would have to be sized for a mech (thus ruining the utility outside of it). If you were wearing hydraulic armor, you might need to work around that slightly (maybe enchanting the gauntlets themselves), but it'd still be usable. Unwieldy, but usable, whereas unloading and unfolding an entire mech for one rusting grasp
and then folding it back up is just ridiculous.
Don't take this all like I dislike the design, it's a cool idea. I'm just too good at pointing out flaws instead of successes. Sorry.