I've not driven a 5.0 or a 14 Eco, so I can't compare at all... But, my 13 Eco with 3.73 gears and taking off hard from the freeway on ramp lights is fun!!
When the light turns green, I'll give it about 3/4 throttle until it just gets rolling. Then mat it... It shifts around the 5000 rpm mark thru 1st, 2nd, 3rd.. By the time you are pulling hard in third, you are over 60 mph and merging with traffic.. :)
Even towing the trailer, on ramp merging is a breeze.. This thing will get up to speed really easy and towing the grades is even more of a blast! It really likes 4th gear and pulling an easy 2700 rpms or so holding a nice and easy 60 mph. If you want to go 65, just press the pedal a bit more. It'll easily do 70 if you just had to.. :)
Coming from an 97 F150 with the 5.4, I can certainly say the 3.5 Eco makes that engine feel like the little 2.0 in my wifes Rav4! :)
Mitch