I got the chance to drive RPG Eco-Boost, sans exhaust while testing their F-150 conversion UCA c/o, Raptor BFG 35" and normal Raptor rear shocks,leafs, frame support. We hit it pretty hard out in Barstow, tore up the fender liners a bit. Gotta tell you it was a hoot to drive. Only 2WD but most of the time never need 4WD anyway. Motor was a pure joy to listen to, high reving, nimble shifting, and with the exhaust gone loud enough to tell what gear you were in, lol.
Now this was a stock Ecoboost, no CAI, no Tune, plenty of power. Not built out like the SDHQ ride - very impressive btw.
I would have selected the Eco if had been available, I am very impressed with the motor and the testing Ford did with it. Tweak it with a tune and CAI and upgrade the exhaust, I think it would kick the 6.2 ass.
In regards to building the Raptor from a stock Eco, I wonder about all the goodies left behind, the beefier drive train/rear axle, Down hill Desent, the upfitter switches, Off Road Mode, They mentioned the locking rear diff that can be engaged in any mode on a true Raptor. I wonder if the SDHQ got the Torsen front Diff?
I see a lot of advantages to building one up this way. I must have $20,000 of slightly used Raptor parts in my warehouse from upgraded aftermarket.
Either way, Raptors rule, however you get there.