[MetalMan]

Using a slower motor and higher voltage is always the best way to go. That doesn't necessarily mean that it is the most practical way. When you add more voltage instead of amps, the motor will automatically be more efficient (as long as the gearing is appropriate). And because of this, the motor can put out more power without heating up as much. So, if you have a slow small motor on high voltage, it can actually produce just as much power as a faster, larger motor (when both motors aren't running hot). This does not say anything about torque, however, because the larger a rotor, the more torque it can output (the kt value is higher).