I test drove the FX4 in 5.0 and Ecoboost. Overall a nice truck. The 5.0 drove almost exactly like my Avalanche 5.3 in terms of power. I didn't notice the Ecoboost to be any quicker on a short test drive. I read on the F150 forums that many ecoboost owners are not getting the MPGs posted. While a few are getting much more than on the sticker.
I'm pretty sure that gas mileage is always going to be 12 or south while pulling until you step up to diesel, then maybe 14.
1997 MasterCraft 205
2008 Moomba Outback
1999 MasterCraft Sportstar OB
1992 MasterCraft 205
1999 Malibu Response LX
1987 Marlin Magnum Skier