Howdy,
I am of Scandinavian descent but never made much of it until about ten years ago, after my father guided an impromptu tour of the Smithsonian's Viking exhibit.
I too would like to see someone back up the HHO with hard numbers. As far as I'm concerned it's
snake oil. If you're a hypermiler it's too easy to modify your behavior in such a way as to significantly improve your mileage, but then attribute those gains to the HHO.
That said, a big guy touring an 800 with 140lbs of luggage (seriously?) is hard to hypermile on the highway. I'd want to see what a non-HHO bike (not a friend's, yours) delivered under similar circumstances.