So, I made a new warrior on a friend's realm and I've been leveling as protection. I've been having a lot of fun doing dungeons and soloing stuff, but I don't like being stuck with one spec. I tried out both arms and fury and they feel so inferior to protection. Shield slam hits really hard, as you are probably aware already, so hard in fact that arms and fury can't compete.
I'm only level 49 right now, but I was wondering when either spec becomes as good or better than protection for solo leveling.