[Knufire]

For the voltage drop, it's as simple as V=IR. The wire, speed controllers, PDB, motor itself, etc all have internal resistance, and the voltage drop between the battery and the motor is proportional to the current. In addition, as the motor gets hotter, it's resistance increases.

This is also where shifting and driver training come into play. A low gear is essentially a mechanical solution to the current problem.

Is there a performance advantage to a 6 CIM drive? Yes. But because of many of the issues you've mentioned, it's not just a matter of designing those motors into the powertrain. Things like battery health and charge, wiring, etc are necessary to realize the full potential of the extra power. This is compounded by the brownout protection that didn't exist last time a lot of teams ran six CIM drives. Could the effort towards solving these problems be better used elsewhere on the robot (assuming your goal is competitive success)? I think the answer for most teams is yes, but YMMV.