FlyingVan,
I will start off by stating I am the manager for a Sprinter dealership in Sioux Falls, SD but joined this forum because I think there is a lot to learn from the discussion of the people using these vehicles on a daily basis. My dealership family also carries the Ford Transit so I have a pretty good opinion on both. Your current situation is exactly what we talk to people about with Sprinter, 600,000+ miles is awesome. I'm sure it hasn't been flawless but still that is tremendous. Talking with my tech on a daily basis who works on a lot of Sprinters, we agree that the 4 cylinder is showing to be the ticket for most people. It has had little to no problems since we have been selling them and has been very impressive on fuel economy. It truly seems to be a workhorse. Also tested the new 4x4 in Colorado a couple of months ago and it is unique and very capable. The ford is a nice clean and well done vehicle as well. I agree that if you go gas the ecoboost is a must. The engine is impressive and has a ton of power. I would expect a pretty big loss in fuel economy though compared to the diesel. I haven't had a ford Diesel yet and I am sure it would be a quality product. However when going with a diesel option I find it hard to go against a Mercedes engine and transmission. Anyway this is my two sense. If anyone ever has any questions I can help answer I would love to do that. I know I will have questions for everyone else!