The Hope is much lighter, roughly 268gm vs 336 gm for Ultegra 6800. This is largely because of the Hope's alloy freehub compared to the Ultegra steel freehub. Ditto for the axle Hope alloy versus Shimano steel.
I believe that you can get a steel freehub from Hope and the Campag pattern freehub probably doesn't have the cassette bite problems as much as a Shimano pattern.
The ultegra FH-6800 model
http://si.shimano.com/pdfs/ev/EV-FH-6800-3605.pdfhas a steel freehub body and an aluminium axle. I don't like the new style bearing adjustment system, because it is impossible to adjust the bearings correctly (i.e. whilst under QR pressure). The freehub body is similar is design to the 'recent' XT version, which has a reputation for breaking.
I like shimano hubs, but for a paltry weight saving they have thrown the baby out with the bathwater, perhaps.
Not all cassettes bite into aluminium freehub bodies in the same way; some sprockets are missing every third tooth and are worse than others (when fitted to the standard spec spline, rather than the stepped aluminium 10s body variant). The biting is certainly worse if the lockring isn't tight enough (as per the factory specs).
Campag pattern aluminium freewheel bodies are better for 'biting' but they have small bearings in them (which don't last as long as they should) and are not immune to splitting lengthwise.
FWIW I am investigating the use of a third-party freewheel body in other hubs such as Hope and Campag; if it works, it means that as well as aluminium campag and shimano pattern freewheel bodies, it will be possible to fit a steel shimano pattern freewheel body to that kind of hub. This should prove to be better value than the Hope type and more durable than the aluminium type, regardless of spline type.
cheers
