There is a decent chance Aamco will put the wrong fluid in. Opinions are mixed on how much it matters, but MB has a specific fluid recommendation. If I were planning to keep the car a long time, I'd go to an indy or the dealer and get the right fluid put in and SDS read. It would cost a bit more perhaps, but then you would really know.

I have a filter kit and the correct 722.6 oil (actually the 722.9 oil which MB also recommends) sitting waiting for the next service, myself. It's shifting fine, but with 105k on the fluid I'm suspecting it could be better. Yes, the dipstick is annoying, but you can make one if you hunt down the measurements here. I bought one through Phil.