[MetalMan]

If you could find a motor like a Feigao 12L or something like that, then you could lower your amp draw on 4s.

The problem with changing gearing to maintain the same top speed when increasing voltage with the same motor is that the motor's resistance is still the same. V = IR, and so since the resistance (R) is the same, when volts (V) increases, so does current (I).
Changing the gearing just means the motor won't pull as much current as if you kept the same gearing when increasing the voltage, but since it's still the same motor, the motor is capable of pulling more current.