Hmm... regardless of where the Merc is made at... friends I know who owns MB (or parents owning one) have complained at one time or another of their poor service attitude. That's for MB in Vancouver (Broadway) and MB in Richmond... not sure about other places. Although I did hear some nice comments about MB on Boundary.
Compare to that, all Lexus owners have good things to say about their service departments. I think probably the most important part in my car decision is to be able to find a great "home" for services and repairs... (imagine my joy when I learned about Rocket Rally
But yeah that's my $0.02