Using the same windows rom here, Shifu 4.3 seems to be the more stable and usable rom around.
Remember to update your radio version too, use always the latest versions, tried android on my phone, looks great, but couldn`t get it to be stable.
(little note on the use of shifu rom, remember to delete any unnecessary SMS you got to your phone, after some months of use, if not deleted your phone might get a lot slower because of them)
Also, previous user, would you please specify the radio you are using, because I usually charge my kaiser everyday or every 2 days, would like to learn your trick. (only complaint I can ever have about this phone is that it is quite slow to change from 3g to EDGE and vice-versa, as I live in a place with phone signal not that strong everywhere)