Tow vehicle and everyday driveability question

I'd drive the '11 for two more years and reassess my mission at that time.

If you can, pull your foot off the gas and see what it does for mileage and stability. Think of it as a vacation for your leg. The difference in gas used between the F250 and an F150 for 15K miles a year isn't that much. I like my F250, it does pretty much everything I want it to do and has been reliable.