You need to look at the price of the engines. In my case I don't have a lot of free money to through out for those other engines . The 617 is a good engine, there is a lot of them out there and they can be had for under $300. with a lot of millage in them yet. I don't know of any other diesel engine that can be had for such low price and high dependability.
One of the local MB mechanics was telling me, that he is planning on putting a 617 in a Dodge Caravan, I haven't looked yet to see if that would work.