try bAD aSS BATTERY .. IT LETS YOU KNOW WHAT USES WHAT..
My TMO GS2 .. not stock Rooted , SU, and running Darkside's Digital Warefare 2.5.1.. basically it's modded 2.3.6 android .. but faster and the battery life depending ..can go from 20 to 36 hours with moderate use.... my longest using it mild was 46 hrs.. i'm assuming with heavy use would still last the whole day.. i have had no issues .. actually less than stock t-mobile... and yes all services of the phone work.. wi-fi calling etc etc.. plus the radio is modded faster.. use to average 6-8 meg now ave. 8-12meg .. some people report much higher.. just not where i live.. i could go on .. but i wont be switching to ICS unless it's proven it's performance... because my phone is like owning a Camero adding a supercharger but you still get 40 mpg LOL