I think people worry too much about IR. It goes away very quickly. Image Burn In is what you want to worry about, and all the new plasmas have orbitors that prevent that. People recommend breaking them in for 100 hours of tv watching (2 weeks @ 8 hours / day approx)... before increasing the brightness settings too high so it breaks in slowly, but even then, i know people that don't even worry about that much either and just plug and play. i would recommend following most break in recommendations found around, but i wouldn't get obsessed about it.
picture quality can be subjective a little, because what you think looks good may not be anothers, however, the lcd/led market has focused on creating the brightness and most vivid looking colors possible OTB... not realistic looking, but obnoxious looking "hyper colors" if you will. that approach destroys any ability to display gradients of colors well, so people then spend more money to have their lcd/led calibrated to look like,.. well, a plasma. plasma tvs have a realistic picture. the blacks are darker as well. just go to any store and judge for yourself. the thing i find funny, you ask any sales person working at a store selling both plasma and lcd/led tvs... they all own plasmas. i have yet to meet one true videophile that prefers an lcd/led. that's not to say there aren't a of nice ones on the market, but they simply don't do things as well right now at this time of technology. more then likely they are the future, but the future is a distant future right now imo.
also, and this is a huge selling point for me, the faster refresh rate make a big difference. even all the led tvs now boasting 240hz (there are some higher but very few can afford them at this point)... motion is terrible. In fact, the more OEMs try to correct it with lcd/led tvs, i find the jerkier the motion seems to get to me. this also plays a huge factor with 3d as well, because the active shutter glasses now need to sync with the tv and that magnifies the issue. if you watch sports, and you want to use 3d, ... you want a plasma.