Check out a W211 forum (e.g.
http://www.mbworld.org/forums/e-class-w211-20/) for better specifics. If you have a lift and are smart enough to research before diving in then I would think you'll be OK. The '05 500 is the M113 engine, and it is not a problem child. I've heard nothing like your BMW experience, just that the W211 is less DIY-friendly than earlier models. Note that during my last trip to Vienna the '04 W211 cab had 480,000 km on the odo. The driver said it was a "strong machine", and that the wheel bearings had been replaced but no major items outside routine maintenance.