[asid61]

I think it's fine. The main breaker is good enough to limit power.
6 cim vs. 4 cim is kind of overblown IMO. If you have the room, put in 6. If you don't, have 4. It really is not going to affect your entire robot as long as you allocate motors to other places first. There's plenty of calculators and the like to help you decide if you will be helped by a 6 cim drive.