First of all, people always associate HD with digital. Native film is HD. the difference between HD and SD in film is how you output it. Any movie you see in theatres is HD. If you take it home and watch it on your little TV, it is SD (assuming it is on any standard DVD).
HDV - the moment any "hd" footage touches tape, it is not actual HD because tapes use a 60i framerate and there is a substantial loss in data.
SD DVDs can not be upconverted to HD DVD content. You cannot insert something that isnt there. Its that simple.
That being said, the HVX does not actually shoot 1080p. It shoots 960 x 720 for the 720p mode, and 1280 x 720 for the "1080p" mode. The pixels are rectangular and are stretched for output. As far as I know, there is no such thing as an HD consumer camera.
Another overlooked aspect is light processing. I have seen countless HVX shots in flat light and it looks horrible. CCDs in general just aren't that good for lowlight snow shooting. 16mm in flat light looks remarkable. No CCDs, just light hitting chemicals. Very natural, very clean.
No doubt, consumer HD looks good and all, but I still don't see the point in prefering it.
And no, HD footage played on an SD tv doesnt look that remarkable to me. I saw Picture This, and I thought it would have looked much better as a 16mm film. And the Level 1 vids just looked like vx footage to me, and I was playing them on a pretty new, big, flatscreen SD tv.
The only occaision that I really liked digital HD footage as much as film was when I went and saw Sin City in theatres, and even that was a digital movie being played on a film format.