I've seen just 5 classes on PTR
Mage, Priest, Warrior, Warlock and Rogue
Mage is not a Duel Class, in BG Frost is Awesome
Priest is fucking nice (Holy) you can beat Rogues in Duels easy. Same like Warlocks. Disc. is good too, because Penance is a good Off. Spell.
Warrior sucks atm, sry...