3.3v vs 5v for longevity and efficiency on LiPo Battery

I have decided to polish my first robot and finish it up (if you can ever finish a robot) (Using a different step-up now LiPower - Boost Converter - PRT-10255 - SparkFun Electronics I might have to go back to the oringal one if I can get another one just for the camera as it really need more voltage for the IR to work)

I am thinking of switching to 3.3v from 5v and wanted some input to see if it is worthwhile.

I can draw a schematic when I get home but here is the basic layout

LiPo(6000mAh) > stepup > Arduino Uno and Camera

Arduino Uno > Wifi or Xbee >Motor Shield

Since I am using a LiPo which is 3.7v I figured I would get more efficiency and battery life without using a step up. I can get a Arduino Pro and the motor shield is already running form the battery. The wifi and xbee both can be run from 3.3v

I would still need a step-up for the camera but the camera isn't always on anyway.

I also might need a better regulator as the one on the Arduino Pro can't handle much current. (150ma)

The idea to last as long as possible on battery when away from the charging dock.

I wanted to review this possibility before I finish my custom accessory circuit board I am making to cut down on the wiring and connections.

Thanks for the input!

;( I ended up getting the arduino Pro and hope that things works. Too bad the regulator on it is so crappy.