I think I smell some controversy brewing!
Y'all: until someone runs _proper_ benchmarking tests, all we have is "anecdotal evidence", which is kinda like saying "well, _I_ tried chewing gum while walking, and it cured _my_ cancer, so it must be a good thing to do".
I have been using TasKiller for about 2 months now, and my battery lasts LONGER as a result of killing apps and widgets running in the BG. Running TasKiller has _not_ affected my battery detrimentally. So does my experience cancel out the experience of others? Of course not, it just means that until someone does some proper benchmarking tests (like those fancy tech blogs do) it's all a matter of opinion.
Install TasKiller (or any of the others) and see how it works for you on your phone.
For the record, I am NOT affiliated with the Dev(s) who made tasKiller or any other Devs for that matter.
I'm not a doctor, I just play one on TV (not really).
Oh, and in closing, it's not always about the battery either, some of us are just paranoid control freaks who feel that _we_ should be the ones deciding what is, or is not, running in the BG on our phones.