It might be worth your effort to slowly switch to B100 (start at B20, B50, work up). Pay attention to your filters and fuel lines, biodiesel reacts differently than D2.
With that said, biodiesel is fine to run straight, as long as it has been properly processed, dewatered, filtered, etc. When I ran B100 in my 240D, it was much quieter, however, there was a small, but noticeable drop in MPG. It also smelled like chinese food
I should also note that B100 has a much higher gel temperature than D2 (and especially winterized D2). As the weather gets colder, you have to pay attention to what is in your tank, and fuel lines, otherwise, you'll be pulling your hair out trying to get your car started.
Good luck