I have been driving a 2012 Super Duty with the 6.2 @ about 400 horse and 420 foot torque. Drove it 14,000 miles the last 2 months, it has had a trailer behind it all 14,000 miles. All 6000 - 11,000 pound loads. Usually an open car trailer, sometimes loaded with full size crewcab pick-ups on the trailer. One trip was a 2000 mile round trip with an 11,000 pound loaded trailer with a 6 foot tall frontal area. Never a problem maintaining 65-77 mph. It has a sort of select shift 6 speed transmission that you can tap down 1 gear at a time and run it in any gear you want so power is always on tap. That tranny is real nice in snowy or rainy conditions when you are locked in 4-wheel drive and you don't want it to downshift and break loose. Drove it 1000 miles locked in 4X on 1 snowy trip and the motor pulls plenty hard driving at 55-70 mph.
I own an Ecoboost F150 and it will pull a 4000-8000 pound trailer with no effort. It has a 6 speed select shift transmission also. I've driven my F150 about 14,000 miles and pulled trailers ranging from 1000-8000 pounds. The F150 has about 3500 miles of trailer towing on it. One nasty trip had about 400 miles locked in 4-wheel and it pulled a 3500 pound trailer with no effort.
The other 2 motors I have driven the past few years are a 2006 3/4 Dodge 5.7 Hemi with 4.10 gearing and a 2009 Super Duty with a 5.4 gas. All trucks get about the same gas mileage towing, 8.5-12 mpg running 65-80 mph, depends on wind. The Eco and the 6.2 never run out of power, just uses more gas. The Hemi and 5.4 will pull hard, but they will run out of power in extreme conditions, they work harder and get worse gas mileage, but not much.
I like the Eco the best because of the power delivery, awesome low-end torque and with the select tranny it just plain motors. The 6.2 has great power, but the delivery is rather sudden and screams right up to redline. The Hemi is a good motor and I liked it alot, but it is the older version 2006 and the new Hemi has more power and I've heard good things about it. The 5.4 will get the job done and I've put alot of hard miles on the 2009, 169,000. It hasn't broke and I just drove the 5.4, 800 miles pulling a loaded car trailer last week.
I got a bit long winded, but that's my gas motor story. WFO