1515 2Y on 6S???

[lincpimp]

If you double the voltage and retain the same overall vehicle and motor speed the amp draw will half. But seeing that you have not changed your overall battery capacity, just reconfigured it, you will not notice much benefit. You may pick up a little runtime, and the motor may run a bit cooler seeing you have halved the current passing thru it. Plus you will stress the esc less, and you could go to smaller wires to save some weight (not really worth it IMO.).