If you can box them effectively (say for example IS Boxer), you will have plenty of dps, and the drop in dps you get will hardly be noticeable. You can run into aggro and mana barriers for faster killing. Given your parameters, I would suggest wiz wiz mage, I would personally take wiz, mage, bard, and enjoy the fountain of mana, as well as a very easy box character, with good adps and no fuzz utility. The bard will make it easier for the tanks to hold aggro. The main reason to take a mage is group coth. I use it even to move short distances into a dungeon. When you break an average of 250k dps, a 5 million hp mob takes 20 sec. In that case, 50k more dps does not matter much, instead you will want faster pulling, faster setup, etc.