I work at an MB dealer parts counter. The largest MB parts dealer in the central US as a matter of fact ($20+ million in parts sales last year).
If your Chrysler dealer is still raping you with the filter, go to any MB dealer and pick up filter 000-180-26-09 (book list $18.50) and it'll be fine.
The AMG cars (as in SRT-6) use 10,000 mile oil drain intervals and the standard MB cars with the 112 engine (non-SRT XF) use 15,000 mile intervals.
Change it at 3,000 if you like, but it shouldn't be necessary. We see very few engine failures at our shop. When we do, it's usually because the owners drove the cars into high water and bent a rod or two. Mercedes don't make good wet vacs but we still booked over 100 flood cars due to the recent storms in our area.
Even when a flood car bends rods, the rest of the engine looks perfect. No blown out blocks or damaged heads.

These are well built motors. I wouldn't worry about the extended drain intervals recommended by DCX.