Just checked Dura Ace compatibility at Sheldon Brown (great site, sad he is no longer with us). The 7800 used an aluminum freehub and had taller splines and took the Dura Ace AND Ultrega cassette. The 7850 went to using TI and has regular splines and takes the typical hyperglide style cassetttes, not just Dura Ace. So if you decide to go Dura Ace, get the 7850 hub to leave your cassette choice open. Mine is a 9spd and has been rolling fine for years and now has the Ultrega 10 speed cassette on it. Good solid hubs.
But I would still do DT over it (weight) and did choose WI over it.
Tzvia- rollin' slow...
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