Plain and simple Ford is just sucking the creme from whipple and Roush just like many other industries do with vendor exclusive content and products. At some point, someone from Ford or Ford themselves will slip out the back door the cheat code on what needs to happen to be able to not only...
FYI the only difference in the GT v DH calibrations is the DH has a tad less tq management. Thats why its a bit faster. I have both tunefiles from the GT and DH and thats it.