Wouldn't the clock speed, voltage settings, usage and prefs(setcpu profiles, brightness, gps enabled, etc) have considerably more to do with battery life then a ROM? In my opinion the average user cant really test a ROM's ability to hold battery life because there are no controlled variables. One user can say "my BB .04 lasts 25 hours" and be running at 550mhz on an ulv kernel, no backlight, 3 text messages total and another user can say "my BB .04 lasts 2 hours" because their running 1.1 mhz medium voltage with full backlight playing homerun battle 3d..
Secondly I believe a lot of battery saving "features" are shared between ROM developers like LWP enhancements and others... I blame battery life solely on my usage and kernel type.. regardless of the FRFXX or CM x.x.x