I've yet to see an LCD panel that I could watch for more than about 10 minutes of video, regardless of HD, or SD. LCD colours look artificial to me, and they still ghost and smear even when given a true HD source. Higher resolution cant hide the technological limitations of the system.
Of course I will conceed to the point that it could be like rainbow effect in DLP projectors. Perhaps some people are not sensitive to it, while others can see the limitations of LCD technology. So if you dont see any problems in an LCD set... thats great. But to me the differences between an LCD panel, and a Plasma panel, assuming both panels are 1080p are obvious and instantly recognisable.
As for price... a 40inch 1920x1080p Sony Bravia is more expensive than a 1920x1080p Panasonic TH42PZ70B. Im pretty sure that panasonic remains the only brand with a true 1080p plasma, rather than a 1080p downscaled to a 1024x768 panel.
The wider choice of LCD panels does bring the price down, but the Panny can be found for under £900 now, and given the choice of a LCD @£500, or the Panny, I'd take the plasma every time.
I've been in TV stores with my GF a few times, and asked her to pick out the plasma's just by looking at the picture quality, and she's picked the plasma's correctly every time.