As per Donnie's post, there's too many variables involved to say 'This Android version will definitely give you better battery life than that version'. Personally, I get better battery life out of JB roms than I ever did out of GB or ICS roms, not that I got poor battery life out of either of those though. And the reason for that is I worked at it.
There's no magic simple A-B-C to better battery life, regardless of what rom/kernel/Android version you're running, you have to experiment & try stuff out to find out what works with the way you use the phone/have it setup.
People who complain about battery life & attempt to pin it on the particular Android version they're running tend to have a really poor understanding of 'how it all works', because it isn't that simple as I've said.
If it's important enough to cause you grief if it's lost, back it up. No excuses
Trolling for thanks is lame
Does Samsung's auto-brightness implementation crap drive you to self-harm ? A solution !
Most retarded thread on XDA in 2013