Date registered: Dec 2005
Vehicle: W211 E320 Bluetec R129 SL500 - $1300 car ........ Ford F350 6l
Location: CA Bay Area
Mentioned: 9 Post(s)
Quoted: 1168 Post(s)
S550 are lovely cars, but also high in upkeep.
I know diesels and they work excelent for me.
However owners of diesel MB who don't know much DIY have hard time to find qualified service.
That also applies to more exotic MB gasers like 550.
Owning ML you should get some experience what is available service for you and then you can make your mind if you want to go for more exotic model and associated cost, or stay with more popular V6.
And be ready to travel.