I had an Airstream Sprinter on that chassis with the 5 cylinder engine. It was our 1st RV and we loved the size and the mileage. The engine predates DEF. You can get a sense of the reliability of the engine / transmission by going to the following site: Sprinter T1N
. T1N is the name for the generation of Sprinter.
A suggestion... Many people buy RVs with the dream of RVing but the excitement quickly fades because of operating costs, declining health, financial setbacks. I would look for a slightly used RV (1-3 years old) on sell by a private owner. You might be able to negotiate a better deal and get a fresher product. Most people are shocked by the initial depreciation and hold on to the unit on principle alone.
There are many deals to be had. WGO is putting a lot of ClassBs into the market and the market is heading for a correction. I am watching the market closely and will strike when the market gets soft.
Just got off the phone with my insurance agent. He cautioned to make sure to strike a deal that reflects/comes close the market value of the RV once you drive it off the lot. If the RV is totaled 24 hours later, that is what the insurance company will payout.