Hmm someone correct me if Im wrong, but there is no 'hard' MT role. All 3 Tanks can soak damage. The differences is that PLD sucks when it comes to pulling due to stances. On the pull its WAR>DRK>PLD. From there it's whatever, though WAR tends to edge out PLD in Dmg by a little bit, wiht DRK trailing a bit behind that. Even more so is that DRK, compared to the other two tanks, requires more thought/effort to deal similar damage.

But beyond that, there is no 'set' MT. Unless SE plans on changing that, they can all do the job effectively, and a lot of the savage fights required tank swaps anyways.