I haven't tried out the mod yet, but in context, it does make sense that the badniks should be made of the lighter aluminum anyway, unless they need some serious strength (steel drills for the burrowbots) or something. Then again, I guess the badniks could be modular as they are (also in context), so I guess certain inter-changeable parts can be different tools you can build, but Mobians can still use as well (drill = Pick, chainsaw = axe, and so on). I don't think Deon would mind you borrowing some notes on how he did it with the Fallout/Wasteland Mod. This can also make the Mobians more modern as well. In regards to swords and such, those can be vibro-blades (like you see in Star Wars: KOTOR or XCOM), knives can be prog-knives (Evangelion), whips can be of the energy variety (like copper electro-whips) or something. We can't forget, using traders and such, consider it like Eggman dealing in the black markets of local regions (even better when the caravan arc is developed even more). Make him seem more rotten. Speaking of trade, we need some noble-class badniks. I suppose variable eggbots can still apply for the role, seeing as they resemble Eggman/Robotnik, I think it would work well (kinda suits his ego too). Eggbot = Noble unit.
I like the idea of natural specialization (initial stats and slow learning). However, allow them to learn a bit quicker via teaching/schools. Consider it like a network update of their programming or synching up their knowledge and skills. It may allow for some abuse, but then again, that's what the starting 7 are for anyway. Take advantage of the crippling over-specialization by making it less crippling if you can "network" (upload/download/dropbox) information between badniks (Elites "educate" mooks). Of course, they will require some points in teaching to do that best. Proper management of that can help make the migrants/backup forces more useful after the first few days of working, provided proper 'education'.
In the meantime, I wonder if anyone will be up to the task of making the tiles for each class best associated with their original counterparts. May require some research into how they look, and what would look best scaled down.
EDIT:
Nice rendering BTW.
EDIT EDIT:
Regarding crutches and such, leave them as they are. I mean, for inexplicable reasons, robots still use crutches when broken apart in the comics/series (though they just explode in the games). So leave it in for the innate comedic effect. It won't affect the Mobians either.