i've also wondered this as i have a 3g jailbroken phone, i purposely didn't install winterboard and my phone has no lag or battery drain, but would loading backgrounder kill the phones battery and lag it as well?
i have lived without backgrounder but it would be nice to be able to use safari while i have pandora on. is just having backgrounder installed going to hurt the battery or lag the phone or only if you use it a lot and often?