I towed from Phoenix up past Payson to the Forest Lakes area with my new 2014 Ecoboost for the first time over Mothers Day weekend and was extremely impressed. My 25' toyhauler was somewhere between 9500 and 10,000 lbs fully loaded with a 4 place full cage metal roofed Arctic Cat Prowler, full water tanks and enough food and gear for 16 people for 4 days between the truck and trailer.
It was no comparison to the 2006 F-150, 5.4, 3.73 rear I used to tow with.
In a couple weeks I will be towing the same rig up the general Crook Trail out of Camp Verde up to Blue Ridge and can't wait to see how it does. The 06 struggled poorly up that grade even with a Edge Evolution programmer, cat back exhaust, cold air intake, premium fuel and with the transmission rebuilt specifically with towing in mind with heavy duty clutch packs, drilled valve body and shift kit.
On Mothers Day I put it in two/haul mode and let it do its thing both uphill and down hill with the engine breaking. I didn't lock any gears out including overdrive and it never broke a sweat. I think Camp Verde will be more of a work out but if it acts anything like it did before I think I will be very happy.