I don't know if you knew this, but Marauders are the best sustained damage dealer in this game. Any nerf to burst damage is a relative buff to them.
I also have a sentinel, dude, and I will gladly sign a written affidavit saying that Connect Four does, in fact, take skill.
Speaking from experience, there was a slightly longer learning curve for the assassin than for an assault Vanguard, and slightly longer still for the Sentinel. None of the three classes are as hard to play as the players of them want you to think.