The F150 MaxTow with the EcoBoost has received many positive comments on this forum. I bought mine two years ago after reading some of those good comments. I opted for the Max Payload as well because I went with a crew cab and I have a trailer that is a fraction over 8,000#. That leave me right about 2,200# of payload.
The truck has performed very well for me. It has been a solid, stable and reliable platform. The EcoBoost does not have the same engine braking that I had on my 8.1L Chevy, but the integrated braking provides an overall better experience IMO (my 2001 Suburban had a good 3rd party trailer brake, but that really was not nearly as good as the integrated brake).
As for towing power the EcoBoost has been great. I have never felt under powered. In fact I feel I have power in reserve.
Whether running empty or towing I have come to really like the engine running at 2k rpm or lower. Makes for a more quiet and relaxed drive. The torque is very good and it has never had to search for the right gear.
Here is a run down on the kind of milage I see.
Running empty at 65 is around 19.5.
Towing at 60 is around 9.5.
In town short commute with a lot of stop lights (always out of sync) is 13.5.
Around town where I get to roll a bit between stops and traffic is lighter is 15-17.
Good luck,
Stu