I've never owned a Ford so have no experience with them. I did own a 2009 GMC 2500 with the 6.0l gas engine in it. In 2012 we towed our 10,500 lb 5th wheel from Kansas to California and back up though the Grand Canyon south rim area and an Las Vegas. On the way back on I40 we were turning 5000 RPM up hill and barely doing 40 mph. I told the wife then that if we ever did this again I would have a diesel. Bought a 2013 GMC 2500 6.6l Diesel a year later.
My point being I was never impressed with the 6.0 capabilities when towing up hills. The tranny downshifted every 10 miles between home and Holbrook, AZ and I could never use the cruise control. With my diesel the tranny downshifted once doing the same route and I used the cruise the entire way.