As far as the additional cost over the 3.7 N/A for fleet purchases, I wouldn't be too sure of that. I'm seeing a *lot* of fleet F-150s running around with the 3.5EB in them, presumably for fuel savings.

For performance, keep in mind that it wasn't terribly long ago - 1997 - that the 5.4 was making 235hp @ 4250 and 335lb-ft @ 3000. The trucks have gained weight since then, but that will decrease for 2015 and probably get back down to where the 1997 trucks were. Plus, the turbo motor will deliver its power at much lower RPM.

I definitely wouldn't rule this one out - especially for people and fleets that use their trucks primarily to haul things around in the bed, and aren't towing heavy.