I installed Stable CSSU (after a clean reflash) and I was using it one week, but found several bugs and had to reflash again. After intensive use (web with flash, angrybirds, etc), when trying to switch of the phone, it did not switched off but freezed or reset. That happened many times in the night when I go to bed and switch off the phone. After restarting it, the switch off command worked properly.
In addition, the responsiveness of the task switcher menu is not as fast as in the stock system. After showing the task switcher you have to wait a little bit before selecting any of the tasks, or the phone will not respond to your selection (althoug the screen notifies the "tap" with the typical sound). I changed the transitions.ini trying to improve this but without success.