Pulling big there will be no comparison to the Duramax, but smaller loads like bass boats will not be a problem. 17.5 MPG isn't really bad if you think about it. Hemi's get worse than that empty! :D
How heavy is your boat Earl? When I think of Ranger I think of bass boat. That shouldn't be a problem if so.
Resale value is still up in the air, but diesels always bring more..that is one thing you can count on. They are great trucks, and get great fuel mileage for a full size.
Welcome to...
I love the look and how those work, but man they are so expensive. Let us know how you like them.. however, I have a feeling there will be no worries on how you like them! :D