The problem I had with Knoppmyth was that I still had to go do a bunch of typing, and because it had done a bunch of other things I wasn't clear on where everything stood.
Gnome's pretty but I don't like it as much as KDE. I haven't used Gnome much, but I seem to understand KDE better.
It probably doesn't much matter for a MythTV box, but since I'm still a noob, it probably makes more sense to have the same desktop on all my Linux boxes.