Tube TV v.s. an HD tv is a way more noticeable difference IMO.
When you can make a tv with the instant feedback of a tube tv with the graphics of an HD tv, I will give you all the money.
That was a plasma v. lcd issue, and it was solved over five years ago. And that was for sports, not video games. And plasma never had this issue. But other than that okay.
This was not solved five years ago. I have friends that just recently bought large LCD or Led TVs. My small, 3-year-old 21inch lcd has barely noticeable delay (I can only tell if I play on a tube tv for a while then switch back), but their TVs are unplayable for me. I'm sure I could get used to it if I stayed with them and played for a few days, but it's really bad. They don't even notice.