No actual experiences (bad anyway) to report, but I have found a truck garage in the nearest city to us, Duluth, MN that does all the UPS & Fedex trucks that use the Sprinter chassis. No warranty work but anything else good to go.
We may find out differently, but from what I have heard from other Sprinter owners if you stay up on the scheduled mx you will likely have few problems. As many as are out there, finding a place to work on it should not be much of a problem.
Now that we have done some travelling in ours, you would be hard pressed to get us out of it.
Good luck