That's exactly the nuts and bolts information I was looking for. When something performs as poorly as these engines often seem to, there is generally a clear engineering defect that is at the root of the problem. MB isn't the first manufacturer to get in trouble by modifying an existing powerplant to get more displacement from it. It's a shame that they aren't replacing these with something redesigned from the ground up to eliminate the problem. I wouldn't want to be trying to sell one of these cars or paying out of pocket to replace the engine again so I guess I will stay clear of it unless it's practically a "free to good home" situation.
Regarding the evaporators, copper sure sounds like the way to go. I doubt MB saved much by switching to aluminum on that part given the number of them that were probably replaced under warranty.