Fwiw
I happened across this article "Five reasons to pick plasma over LCD"
http://www.digitalhome.ca/content/view/2197/206/
Mostly reiterates what people have said above - I assume it reflects current wisdom in this debate. I cut and paste the relevant parts - the article has a bit more info.
The following are the five reasons, with a brief explanation for each, why Digital Home believes plasma televisions are a superior choice to LCD televisions for consumers wishing to purchase a 42” or larger flat panel HDTV.
Superior Colour reproduction - Plasma displays are described as self illuminated because the individual phosphors are lit up when an electric current flows. LCD, on the other hand is described as a transmissive technology because the backlight passes through a series of plastic filters in order to generate various colours. This difference means that a plasma display covers a far greater area of the visible light spectrum and delivers more dynamic colours.
Superior black levels – The richness of an image simply cannot be conveyed if the colours are washed out which happens when good black levels aren’t present. Good black levels are important to provide a sense of depth. With poor black levels, shadow areas look gray and washed out, making the picture look flat. Plasma is capable of superior black levels because it achieves its “blackest black” by turning off the necessary pixels. Because LCD has a constant light source, black is achieved by applying a filter which blocks most but not all of the light. This difference means that the best LCD panels can only reproduce a dark gray as opposed to black.
Better viewing angles – when buying LCD televisions’, buyers often encounter the term viewing angle. With LCD televisions, as you move off centre, the contrast levels fall. At a 45 degree angle, contast ratios for an LCD televisions drop 80%. To witness this phenomenon, simply stand in front of an LCD television and slowly move to the side of the room. As you move away from the center the image will appear more washed out because more light is spilling through the plastic shutters. With plasma, the contrast ratio is constant regardless of the viewing angles so the picture looks great regardless of where you are sitting in the room.
Improved clarity - plasma trumps LCD in picture clarity for two reasons. First the improved viewing angles of plasma mean no washed out images when viewing from an off-centre position. The second reason for greater clarity is plasma’s faster response times. Although response times vary, plasma panels typically have much faster response times than LCD. Slow response times mean that fast action onscreen can lead to a trail or shadow effect as something moves quickly across the screen. A hockey puck for instance will have a momentary trail when it is shot. Plasma’s faster response times mean the absence of trails or shadow effect.
Proponents of LCD television will argue that next generation 120MHZ LCD panels have pretty much eliminated trails or shadow effect and we would agree however, consumers should note that most LCD panels available for sale today are not 120 MHZ panels. Prepare to pay a premium for 120 MHZ LCD panels.
Lower cost – – Visit your local big box retailer and compare the price of a 50” LCD flat panel and 50” plasma from a major manufacturer and you will generally find that plasma is less expensive.
Common reasons cited for picking LCD over Plasma
LCD flat panel proponents typically cite four reasons for choosing an LCD flat panel over a plasma display panel. We examine each argument individually and find there is little if any truth to them.
LCDs don’t suffer from burn-in – “burn in” or permanent image retention is the number one reason why LCD is often touted as being superior to plasma. While "burn-in" can occur in modern plasmas, the effect is temporary. In a 48-hour torture test, research group IDC, in partnership with Imaging Science Foundation (ISF), tested three plasma TVs and burned in clearly visible images from a game menu. Once they created burn-in, regular video material (a DVD movie set to continuously loop) was played through the sets for 24 hours and the image completely disappeared from all three plasmas, leaving no trace.
The researchers concluded that unlike early generation plasmas, where those type of images would not go away and could actually "burn" onto the screen, modern plasma TVs enjoy a combination of more robust screen materials and subtle image-shifting technologies that have rendered this issue moot.
Lower power consumption - the statement that LCD panels, of the same size, use less electricity than plasma is a fallacy. Since an LCD is backlit with a light that is on all the time, the power consumption of an LCD panel is constant. With plasma, the amount of electricity is variable because each glass bubble is turned off and on depending on what is happening onscreen. If every bubble is turned on (a rare situation) then a plasma display does use more electricity. Since most bubbles are not turned on at all times, the average power consumption of a plasma and LCD panel (of the same size) is almost equal.
LCDs last longer –the half-life of most plasma display panels is 60,000 hours. The half-life is the estimated amount of time you would need to spend watching television until the panel brightness was reduced in half. A 60,000 half-life equates to 6 hours of television viewing per day for 10,000 days or 27.4 years. Research has shown that LCD panels may last slightly longer than plasma; however, we doubt you’ll bother keeping any television for 28 years! In case you’re wondering, the average half life of a traditional tube television purchased in the last twenty years is about 30,000 hours.
LCD superior in brighter rooms – simply speaking plasma is glass with white phosphors behind it. The result is that a mirror effect can take place when extremely bright light shines on plasma. This mirror effect can make it more difficult to see the images on the screen under extremely bright situations. This situation often occurs inside a big box retailer’s showroom which can be as much as five times brighter than a typical living room! In your average living room where the ambient light level is much lower there is little need for a “brighter” panel.