Our F150 Egoboost is like Donna's, except it's a 2013 and we have a cap on the bed. We get 20-22 mpg when we're not towing our Casita. It drops when we tow to 16-17, which is what our 1998 F150 (V6) got on a good day, without the Casita tagging along behind. (We didn't call it the Big Blue Gas Hawg for nothing.)
Of course I wonder what the hit will be on the Egoboost's mpg when we're towing a 21' Escape instead of the Casita, but, like Donna - we love this truck. Our dog's kennel rides behind the driver's seat and she is travels much better there. The integrated tow package exceeds our expectations and the little back up camera is handy... and the gas mileage not-towing is only a couple mpg below what we got with a 4.0L Ranger.
We drove the Big Blue Gas Hawg for 15 years. We expect the kinks will be worked through on the aluminum F150s long before we're ready to upgrade again.