I honestly wouldn't recommend that.
While it might reduce the heatup and give you more torque, you'll get
serious problems with microstepping.
Look here for more details:
http://hydraraptor.blogspot.com/2012/04/stepstuck.htmlLow current microstepping alleviates the problem *at 12V* but does not fix it.
The higher the voltage, the worse the issue, because the lowest current step will have an even lower current.
Edit: Also, bear in mind that there are limits as to how fast you can print that aren't related to the mechatronic part of the machine - namely, the extruder. On top of that, once you cross some magic threshold, you'll have serious trouble getting vibration-related artifacts out of your prints. In short - as tempting as it might sound, "more" is not the hammer for every nail. More speed, more volts, more amps... If you want good prints, stop thinking in those terms.