Welcome to the forum!

I haven't experienced any problems with the windshield wipers, but I would recommend checking "both" fuse panels if you haven't already. I am not positive, but I think they are two independent motors, so the chance of dual motor failure sounds low. (Can anyone enlighten us?)

My 6 is pretty rough at idle. I think it's a standard feature. Even the CLS63 Black Edition has the same rough idle, and it costs $$$$$.

I have yet to experience drivetrain whine, and I can't really give you any input.

If you're in Georgia, you should join us for the "Tail of the Dragon" this fall.

Happy motoring!