[Al Skierkiewicz]

Andrew,
From an electrical standpoint there is not much to gain from turning one motor off. With both motors supplying power, the electrical load is effectively shared between the motors. There are some electrical losses but it becomes a wash as to whether the electrical losses overcome the mechanical losses of a motor in the drivetrain but not powered. As to electrical load from the motor that is off, those are negligible since there is no electrical load on the motor in "coast". Since the motors are about 90% efficient transferring electrical to mechanical power I think you are talking relatively small savings overall. By sharing the load, you don't have one motor at a much higher temperature than the other and with individual currents being lower, the electrical voltage drop in the wiring is smaller. It is like feeding a single motor with two wires in parallel. However, it might be useful if you wanted a "turbo" overdrive for high speed running at the push of a button, but with the normal playing field size the advantage of double speed is small.