I don't remember what the battery was at when I installed 5.1, but I know it wasn't 100%. I've been somewhat disappointed w/ the battery duration. I'll make sure it's at 100% when I install 5.2; hopefully it will make a difference.
In my case I dont see a difference from my autonooter and 5.1. Just flashed to 5.2 which has the overclock up to 1.1ghz so we will see. Although even at 800mhz it is plenty fast so that just may be overkill anyway. But I can say that battery life is good. But I will add I dont think battery life on a NC is great to begin with. Nothing like my ipad. Bob