How about Somerset?
Hi. I've got to recommend my MB dealer -- Millennium MB, in Bridgewater/Somerville area. They are really terrific guys, and are on an "enthusiasts" wavelength. I'm having them do some custom work on a gray-market vehicle, something other MB dealers wouldn't touch. And, of course, their work is first-class -- you can't imagine how finicky I am.
P.S., I've heard that Princeton (I think they're really in Lawrenceville) MB is also "enthusiast oriented", but I've also heard mixed reviews of their work quality.