I've had my nook rooted since 1.4 and get good battery life. The main issue, I believe is to modify the rooting so that adb doesn't run continuously and then use WI_FI Locker to turn it on only when needed and turn it off afterwards. To change the default to adb OFF see Naerymdan tutorial
http://nookdevs.com/User_talk:Naerymdan. The info to change the default is under: Reduce battery consumption .
Don