The E55 got the 476 HP engine. But trust me, there is not much difference in power vs. the SL 55's engine.
I don't think we'll see a E55 AMG 4-matic...ever. Might be a problem with the torque/power and it would add some additional weight too. The ESP on the E55 does a pretty good job as far as I read and I'm not sure the E55 would make a good winter car.