I had a lot of the same concerns before I bought my EB. In Houston (and Calif) there is a guy on the radio on Saturdays called Jerry Reynolds. He is the Car Pro. I looked him up on the 'net and sent him an e-mail.
I have heard him rave about the EB and wanted to ask some specific questions about it. He answered me in less than an hour.
He said that Ford finally has done it right. The engine is very durable and had power when needed.
The selling point of the EB is you get V6 economy under normal driving and V8 power when you need it.
I found that to be true this past weekend when I pulled my 33' travel trailer to the lake.
I have 3000 miles on mine now. I get 17.5 MPG without even trying to coddle the truck. I am anticipating better mileage as I get closer to 10,000 miles.
I got 10.2 MPG pulling a 7000# travel trailer and the F150 pulled it like a champ. Going up a hill at 35 MPH in 3rd, I accelerated and actually gained speed, but did not lose 3rd.
This truck loves 6th gear. It gets in to 6th at about 40MPH and will stay there as you give it the gas, as long as you don't punch it.
This EB engine is not new (in the F150 in 2011), it is just new to the F150.
It was in one of Ford's SUV's before 2011.
So far I love mine and am extremely pleased with the towing power it has.