I'm running Bugless Beast (could not love this rom more) at 1Ghz and setcpu with an aggressive profile structure:
Charging 500 max & 125 min
Sleep 250 Max & 125 min
Power 999 max & 500 min
I am getting phenomenal battery life. It is better than when I was stock. I think the Beast is a very good rom that helps battery life better than some others (that is a very subjective statement though). I think the real difference is the Setcpu program and the sleep settings.
Yesterday after very heavy usage that included GPS, movies, surfing, music and many emails, I had 50%, or was it 40% (I can't recall) at 11 pm after being off the since 5:30 am charger. I think it was 40%. Whatever it was, it lasted all day and then some.