With tech you can find schematics to build the mods that you slot into them, I am not at full crafting yet nor have I tried to craft any of the mods. I doubt they will be any better then the mods you can buy in honest so that isn't much but then again it would be hard to work on your own arms or blades hidden in you arms, though you could work in them when they are unequipped that would be nice. Though personally I think there is too much damage in other play styles, they would need to be reigned in before the arms can be said to be balanced.That's my biggest issue thusfar. Why the hell can't I work on them myself as a Techie? I have 20 Tech and I can't even tamper with them a little? Really?
Outside of that the two things I want to see most is I would like it if not every attack broke stealth and the gorilla arms have only helped by 6 Body netrunner open a single gate that needed a body of 12. I would like to see a bigger multiplier on the strength to open doors and take over cars at least with the legendary set.