I'd just like to add some more insight on the common complaints of the M104 engine: bad engine wiring harensses and head gaskets that leaks.
These are one time expenses that are not repeated again and again and again over the lifetime of the engine.
The new wiring harnesses are made with regular insulation that doesn't fall apart, and the newest head gaskets are made with oil inserts where the oil passages are that prevent it from leaking again.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".