I've been through a set of P7000 Supersports, and SP8000's. I have a set of Pilot Sports about to go on when the 8000's are toast.

Mercedes normally wear both edges of the front tires, and to a lesser extent, the middle of the rear tires. Lowering will add more wear to the rear inside but that's about it. You can get the camber within spec up front, but usually it's a bit negative in the rear. Having a PROPER alignment is essential. I only let the Mercedes dealer touch my car for alignments. Almost no independent shops can do it right (unless they happen to be a Mercedes specialist.) If they're not using the steering box lock tool, and the spreader bar, it's not done properly (IMO). BTW - I request the computer printout from the dealer with before & after numbers, so I know exactly where it's at. I'd bet a lot of complaints about tire wear are more related to alignments than lowering without camber kits, but that's just IMNSHO...

BTW - most of the solutions for rear camber kits are in the $200-$400 range. I'd say if you can get the rear camber below -2.0* (preferably about -1.0), that's just fine, leave it alone. If you're at -3.0 or -4.0, yeah, a camber kit might be in order....