There are a few Sacramentans who hang out on this forum. There are a couple of pretty good shops in town as well. My two favorites are Silver Star Motors (John) in Fair Oaks and Stephens Service Center (Tom) close to downtown Sac. Both John and Tom have serviced my cars (a 240D and a 300D - John worked on those, and now a 300E - Tom's shop works on that one). Tom was once the service manager at the only MB store in town, Von Housen Motors, but broke away to do his own thing and does it very well, IMHO. One qualification in your post might be difficult. You wanted someone to work on your car who is tied into this site. I've never asked either John or Tom whether they spend time here, but I doubt it. Both run very busy shops and probably simply go home and go to bed.
There are four or five other shops in the area that I know of, but haven't tried them and probably won't. There is a Mercedes shop along 80 out your way (can't remember the off-ramp, but near Roseville-Rocklin), that I understand is owned by the Von Housen group. You might check them out, although my gut tells me that their hourly labor rate might be a little steep - sort of a dealership addendum.
Welcome to Sacramento. Now if the snow level would just drop we can have a real serious ski season this year...
2003 Dodge Durango SLT
2002 BMW E39 530i Sport
1988 Mercedes 300TE
2003 Chevrolet Suburban