our valor 65 crew roll with 2 mercs 1 heal 1 dps 1 juggernaut and a sorc and we have yet to loose a game, also 4/5 nightmare EV.
merc/sorc/sniper is the way to go if you want to dps and got friends to play with they annihilate all the current dmg classes atm.
and once you get 2/5 raid set pieces (15% more crit to tracer missile) you will really feel overpowered since you can spam them for a very very long time