I own a 2011 FX4 Supercab 5.0L and I've driven my share of 5.4L's over the years...Everything from the old 2v 5.4L all the way up to the 3v 310hp ones.

There was a signifigant difference between the 2v 260hp 5.4L and the 3v 310hp 5.4L but I think it was mostly related to the 6-speed tranny vs the 4-speed in the old unit.

I can comfortably say though, Without question that the 5.0L is superior any of the 5.4L's I've driven in every way. The only 5.4L I've ever driven that I think may have given the 5.0L a good run was a friend of mine who had some work and a 5-star tune on his. He was laying down 14.5 to 15.0 1/4 miles, but it was not stock. Most 5.0L F-150's I've seen run about those times without having a tune or any work done to them. The 5.0L in my experience feel's equally as torqy in the lower/mid range as the 5.4L does...But loads more powerful in the mid/high range, and ontop of that it gets better mileage. The 5.4L's a great engine, and I've seen some that went well past 400,000 miles...I hope that the new 5.0L will share the same reliablity charcteristics of the 5.4L...But only time will tell.