Motor usage question on 5s lipo

[lincpimp]

Ok, ZPB, you think that the lover kv will be offset by the higher gearing thus not really affecting the amp draw? I wondered about this, as the motors are somewhat close in kv. Does it matter how fast the motor spins? Is there a rpm point where bl motors are more effecient? I know that it is generally said to keep most bl motors under 40k rpms for better effecientcy, but is there a point if the motors spins too slow and the effecientcy drops?