I have very limited mechanical exposure to Mercedes, but own three and love them all. I have an 87 260E with 280K+ miles and it is as strong as ever. The only item I would consider a non-typical regular maintenance item is the new radiator I installed.
I am very proactive in my belief on maintenance, but my income is directly commensurate with my ability to drive. I can honestly say with the three Mercedes I have now, totaling 483K+ miles, not all by me, I have not encountered anything I would not consider to be regular, prudent maintenance. Maybe I'm lucky!
I would also have to believe that some parts wear out due to age, and not necessarily mileage. Not sure about that one, but am inclined to belive so.
I wouldn't hesitate for a second buying a Mercedes with so few miles! :-) Assuming of course you know the maintenance history. I know my 260 is worth at least another 280K miles.
Just my opinion,