Just for the sake of arguement let us look at the big picture, Mercedes has always been at the forefront of diesel technology, so roll your clock back 30 years, there was the 240D manual, as simple and primitive as it gets, now compare the 240D to a 98/99 turbodiesel, more power more performance with an order of magnitude more complexity.
Now compare the 98/99 turbo to a current CDI, side by side with hoods open the E300 looks almost as primitive as a 240D next to the CDI, again an order of magnitude more complexity.
I am not against progress but this level of complexity combined with Mercedes' miserable reliability history makes the CDI a 100K/warranty period car. For me paying $60K for 100K miles service is a bit too much, soooo, thanks but no thanks.

Vahe
240D 77 350K
E320 97 73K