My batteries don't stick out. My back cover snaps completely shut and I'm able to put my diztronic case on it, too. I bought it a little over a week ago. I had them just in case at the Chicago Auto Show.
I prefer spare batteries than external battery packs and what not. It was very useful at Universal Studios. I was able to just pop the dead battery out and put a fresh one in as opposed to plugging a battery pack in.
I just got my Anker batteries last night I will be doing my "scientific" experiments with them tonight to compare the two.