well, ive taken it to concerts and recorded on and off over an hour and it took about 1/3 of my batt.... so it is a significant drainer
edit: ive noticed SIGNIFICANTLY improved batt life with the new lernel im running today.... 2.6.35.10-SavageKernel-V1.6-BFS-HAVS #3
give it a shot, but make a nandroid b/u first lol