Scooter, I was referring to those who saw no difference. I see a difference with an upconverting SD DVD player. I was just suggesting that those that did not may have watched a DVD backup that should have been on a DVD-9 as yours was.
I don't have any real opinion on the subject of upconversion. But it sounds like some folks are mistakenly comparing upconversion on their player vs upconversion on their digital/fixed-resolution displays (and in some cases, CRT RPTVs that also force upconversion). For instance, one example mentioned seeing little-to-no noticeable difference on a plasma display -- well, of course, the difference will be very minor, if at all noticeable, w/ a plasma display (or LCD or DLP, etc). Some sort of upconversion (and/or even downconversion, if the display is not native 1080) is happening from source to actual output w/ such displays no matter what you do.