Yes its supposed to drain the batteries faster with the AFS on due to the system using the servos more frequently to adjust the attitude of the plane. I wouldnt know mine is unplugged and has never been plugged in. I havent heard of anyone using it much here either in the forums. Most feel the feature is useless and unpredictable unless used under ideal conditions. Most also agree that it wont help you in the long run to fly better. Once its turned off you are going to have to learn to fly all over again. May as well learn to fly the right way from the start.

The Nexstar has great flying characteristics for a trainer plane, you wont need the AFS. Just practice religiously with the Realflight sim and you will do just fine.

Happy Flying,

Sean