P7 with no contest, the P7 has 4 LED's packaged into 1, so @900lumens, compared to 275 area for a R2.
Difference is 12watt draw on the P7, compared to 3Watt so 1/4 the run time.
Dealextreme.com do torches ( about to order a P7 ) and sometimes the LED's for real cheap, just buy the torch I say strap it too your helmet / bars and job done.