I think LOTROs Captain class was the best support class I'd ever seen in a game. They could spec as tank, healer, or DD and subsequently support either of those roles best, while still being able to support the rest of the party. How were they balanced? They couldn't do any of this stuff to themselves. 8 man content always needed a captain but you could spec to be any of the 3 roles. I really like it and think it would work well here.