i think that most of the misconception surrounding battery life are from those who install backgrounder and leave it at the default setting of all-apps. first thing i did was reconfigure it for only the apps that i want to run in the background.
my performance and battery life are unchanged. actual to be honest, my itunes backup and sync appear to be much better and more inline with my iphone 4 performance, but it is probably just a plecebo effect.