Louis I don't know much about ZF and Ford but in general I don't know any proponents for DMF. I have never heard of a beefed up aftermarket version of a DMF. But, that doesn't mean much really. Just did not want you to feel unappreciated with no responses.
I expect the busticated thread to get moved soon as the 6.5 questions ease off.
Seen power strokes with tuners on them eat clutch after clutch and the only thing that would hold up was the south bend kit with the kevlar pilot bushing. This experience comes from the ZF 6 speed, but I still feel it is valid. If the truck is stock I thing the Luk kit would hold up just fine. My vote goes to South Bend.