Actually the pet won't fight for you when you sneak it in the back door, they just follow you around. Whether or not the stat benefits are active, I don't know. I don't think so from the amount my rogue died They show up on your ID, but the devs posted that they would be disabled.

This being said, when there are pets in the arena, it doesn't make it seem any more cluttered than without, which I understand was the main concern.

On warrior, running around smushing mages is like a rousing game of whop-a-mole - fun for the warrior, but I imagine not so much for the mole, I mean mage. I haven't tried sorcerer in PVP yet at this point. My rogue manages to kill quite a bit, but also seems to die over and over and over, so I just find myself sticking to warrior for this game.