I have a 2012 DC with the 4.6 up to 10K miles on it and I have no regrets. Over that most of the driving is a short commute to work but I sprinkle in a few 300mi round trips at 85mph and I get 14 or so normal commute and around 19 on the highway trips. Not ideal but I certainly won't complain with the power to performance ratio I feel the 4.6 gives me. The fact I can tow anything is really just a bonus
My mechanic (ex-Toyota mech) was my research tool and he said unless I had specific requirements he would always buy the 4.6
As for the fuel economy comparision between a 4.6 and 5.7 :-|
My opinion...Really? You bought a pickup truck with a V8...who cares? I have been a pickup guy since I was 16 and haven't noticed very much improvement in gas mileage over that time. You want good gas mileage in a V8 drive 50-60mph highway and don't take it in the city.
For reference my old 1976 (360) /1985 (318) dodges got nearly identical mileage as my 2012 Tundra but the Tundra is way nicer to drive
To sum up 30+ years later a V8 is still a V8