I am sort of in the same boat, however I also use the truck as a daily driver putting 120 miles a day, 5 days a week on it. My current truck is an F150 3.5 EB, getting roughly 17.5 MPG, on Premium. I run Premium in summer, and 87 in winter, especially when towing, so comparing the costs for fuel is a non issue in my case. I have wondered about fuel issues as one thing I have come across a lot is that the fuel system is very sensitive to water, one drop can kill it. Aside from that, though, and since there is a water separation unit at the tank, and if maintained properly should prevent it from happening, the engine itself has been pretty reliable, as well as the rest of the truck. Since I am looking used, and live in rustland, I ruled out used Ram, as they are all rust buckets up here. There is no way I would ever buy another GM, so those are out, so have only been looking at the Superduties.
I used to have an F350 7.3 Powerstroke, and it was a rock solid monster, and would love to get another one if I can find one with low enough miles and pampered. Good luck in what you find, I know I will be looking at them hard, and not the gas either, I just know I would regret it.
