[Chris is me]

6 CIM drive, single speed geared for 13 FPS actual (measured) speed. 6.11:1 on 4" Colsons, if you want to do the math yourself. Treaded them for regional 2, plain for regional 1.

We had no problems tripping our breaker all season, however we did design our entire robot around preserving current. We modeled how much air our pistons might use and went with 4 plastic air tanks in order to leave the compressor offboard. Most teams only leave the compressor offboard if they have weight problems, but I think current draw is a much more important reason to consider leaving it off. To keep current draw low we used relatively few motors across the rest of the robot. Other than the drive we had just one BAG motor for the intake, one mini-CIM to drive the arm, which we partially balanced, and one mini-CIM to retract the winch, which we geared down significantly to reduce the load on the motor.

We never did take off two motors to compare the performance of a 4 vs 6 CIM drive, so all of these opinions are pretty worthless... but purely subjectively, the 6 CIM drive seemed to accelerate faster and felt more responsive than a 4 CIM drive. Interestingly, with regard to the 40 amp breaker, we found that when the 6 CIMs stalled against a heavy load, the 40 amp breakers tripped less quickly than with a 4 CIM drive. Obviously part of this is because the load is distributed across more motors, but the drive was fully stalled so each motor should have been at its max current draw. What we later realized is that with more motors, the voltage drop was greater, resulting in the motors drawing less current at stall (and also having a lower stall torque at the lower voltage). Thus, the 40 amp breakers are less of a constraint in our particular configuration with 6 CIMs than they are with 4.