After updating my firmware to KF3 the other day, got really bad battery drain, Android OS cpu total was at around 2.5 hours yesterday, my phone was completely dead after less than 24 hours, with my normal usage (actually probably slightly less because of i knew of this issue) I'd usually get about 2 full days, and then charge over night using KE7.
After settings kept force closing whenever i tried to do a factory reset, i decided to give a custom Rom a try in my frustration.
Now running Cognition S2 v1.12 (which is 2.3.4 - KG1), which seemed like one of the easiest to flash. Now getting much better battery life with similar usage to yesterday, my battery is still reading 76% (was around 40% yesterday from memory), Android OS cpu time is down to 13 minutes at the minute.
Pretty happy now, and was very easy to install, as i'd already rooted the phone (which is a simple process anyway). Obviously i've not used the phone a great deal to compare it against a standard rom. But i've not come across any issue yet, and it seems like the guy on xda is updating the rom pretty quickly.
Downloading v1.13 now, to update to when i get home, apparently an issue with flash.