My buddy and I had the same argument. On paper, the Sammy should murder the Panny, due to better contrast ratio, and a higher video-processor, but here's the reality: We stacked the Panny ED and the Sammy ED side by side, hooked up identical DVD players with identical cables and stuck Starwars III in at the same time to compare. The Panasonic slaughtered the Samsung, despite not matching up to it in specs. The black levels were superior, the clarity was superior, and the colour was supreme. The Sammy is a nice "Bang for your buck"model, but it just couldn't compare with the Panny's levels.
For those of you boys already burying ED, consider this. Only about 30-40 channels on cable or satellite are HD as of yet. Those of the "suckers" who have bought ED are going to get a superior picture from the non-highdef channels in comparison to those of you "masters" with HD plasmas. :D:D The ED models don't have to scale the SDTV picture up as high, and so the effect is much less grainy than on an HDTV, which scales enormously, particularly if you have it set to 720p all the time, which is the best viewing for the HD channels.
Stick the Pany 50PX500U and the TH-42PX50U model side by side with HD playing on both, and I dare you to find a huge difference. The only noticeable difference is in black levels, and even that is minimal.
Those of you who chose HD plasmas are most likely going to have to pay the same amount for an ATSC tuner box as those who purchased ED plasmas, when everything goes completely HD in 2009. Very few HD plasma models come with the ATSC tuner, unless you're buying a higher model Panny or Sammy. So nyah. :D:D:D