I did a lot of research on TV's when my parents were looking for one and they ended up getting a 50" Panasonic Plasma. It is a level below that S1 but still 1080p and it was $900. The picture is really really good and with the new technology burn in is not really a problem and they are 600Hz if that was one of the things you are worried about. The only problem with moving them is the screens are glass so they say not to put it on it's side but that is just because the glass is easier to break when it is on it's side. My parents ended up taking theirs home on it's side and it was fine, you just gotta make sure you aren't going off roading with it or anything. The plasmas do burn a bit more energy and get hotter but you can still find some that are energy star rated and to me it is worth the extra money. The life of the gas in the plasmas now is at least 60,000 hours now and that is similar to the expected life of the back light in LCD's.
Really for me it would have to do with price vs. performance and in the larger sized tv's the plasmas were much cheaper and great quality, and the Panasonic Plasmas are some of the best. For my TV I got a 32" Sharp LCD it was $400 a year ago and looks great to me, I am sure you can even find them a little cheaper now. Once I get a house though I might have to upgrade to a 50"+ and put the LCD in the room.