I hate to get into this discussion as feelings and impressions are hard to argue with.
Seventeen inch factory wheels are less of a compromise than are 18 inch wheels. I am at home so I can't verify whether there are different part numbers for the AMG suspension control arms, but I can say from experience that all the control arms in the rear have changed numbers almost every year as they stiffen the bushings and links themselves.
Three and a half sets of tires. I won't ask how many miles. I just stress what a compromise it is to be driving on tires that need to be replaced. I haven't personally owned a car with less than 16 inch wheels on it in 14 years. They all were factory wheels and even at that I have had to put up with tire noise and driveability problems way more often than the higher profile tires. My current car is a 97 BMW 540i. It has the smaller wheel option with 225/55R16 tires. I have been real close to buying the factory sport wheels at 17in., but I'm not because I recognize it as a vanity issue and I'm not going to put up with the problems it causes.
When I upped the tire size on my 928 Porsche from 225 to 235 I had to increase the toe-in about 4mm (more than the factory tolerance) to keep the tires from wearing on the inside. The Carrera I had before that had perennial tire problems. BTW my wife has always driven the big MB which until the BMW was always our out of town car.
Bosch Master, ASE Master, L1
33 years MB technician