There is a huge difference among technicians whether they are independent or work for a dealership. I've had some really bone headed things done by MB dealerships that would never be done by a Stu Ritter.
On the other hand, I recently had some work done by a technician in a huge MB dealership. He probably averaged as many head gasket replacements in one week as my previous dealership did in a year. It's apparent he knew what he was doing. Experience is everything.
I wouldn't go to an independent unless they were one of the few that had a national reputation.
I used to take my BMW's to a dealership for a lot of service because they treated me like a car enthusiest rather than a naive owner. The only time I don't do things myself on my MB's is when I can't handle it.