I'm one of the few people that believes Gladiator is still superior to pure Prot. Both builds are complete garbage, but I think playing pure Prot is the most degrading way to play a class that's supposed to be all about damage. At least with Gladiator, the damage burst with Heavy Repercussions + Shield Slam + Shield Charge after a Charge is still pretty brutal. Prot damage just tickles people no matter how you set it up.
I just don't understand why anyone would want to play a Tank spec in PvP where all of that survivability goes out the window once you play on a team of healers. If you want solo play, just go play a Death Siphon Unholy DK.