If you find a quality independent service guy the costs are not appreciably different than other cars. I've owned 3 in the past 15 years and have not had anything out of the ordinary happen to them, admittedly a small sample. Cracked front windshield with OEM replacement (need it for the rain sensing wipers) was $500, I don't think that is that different from what an Acura would be.
You mention SUV -- those will require more thought. My in-laws still drive the '02 ML500 I gave them back in 2005 and it has worked very well for them with 2 repairs about $1k over that time.
2 items to watch for:
-the Nav unit will go, its only a matter of time, and its an expensive fix. Almost worth getting an extended warranty just because of the electronics if you intend to keep it.
-air suspension -- I would avoid it, it will fail and it will be a very expensive fix.
Otherwise MB's last a long time -- mbtex is pleather, but man it holds up.
If you have access to a good independent who can look it over for you, I wouldn't be scared away. Problems tend to surface early in ownership, if it went 5 years without any mechanical problems you are probably ok with the basics.