I agree to an extent. I have never seen anything worse than minor retention on modern LG panels, but Panasonic and Pioneer will always retain less, last longer and perform better.
But before I just go off and say you should have bought this or that, let me actually answer the qestion at hand.
Plasmas are prone to image retention, not because of the nature of the set, but fr several Changeable factors that I will list here:
1. Operating Temperature
2. Pictorial settings
3. ISF Calibration/Break in
4. Power mode
6. Whitewash and other extreme measures.
Operating temperature means if I were to stick a thermometer into the panel, it would be the temperature it read. The LOWER the operating temperature, the better. Operating temperature is affected mainly by picture settings and power mode, which I will get to defining later. Just know that the lower the operating temp, the more resistant your set it to retention.
Pictorial settings are the most significant thing one can to to keep operating temp low. By using my recommended settings for the Pioneer PDP-5010FD, for example, operating temp went from 126F to 79F. There were no service menu functions involved with those settings. Make i a piontwith your panel to keep color temp low (warm), contrast about 50%, as well as brightness (less than 50% if you can help it). Color I usually keep at 30% or so, but it depends on the panel. I tend to keep all contrast and brightness enhancer modes turned OFF. Most panels come set for the showroom, with settings overdramatized. This causes a rise in operating temperature, which increases the risk of retention. The best Picture settings come from an ISFccc calibration, which can only be done by an ISF-certified professional. Be prepped to spend $250-$350USD on that service depending on your location.
ISFccc calibration drastically improves display abilities performance-wise, power consumption-wise and opertaing temperature-wise. and ISFccc calibratin will have your set looking the very best it can in the environment it's in (keeping in mind that a cool, pitch black environment is best for these sets). This is basically taking more drastic measures than simply using my recommnded settings. I professionally ISFccc calibrate sets in my free time, so my recommeded dark-room settings are usually as accurate as they get.
Power consumption greatly affects how well a plasma can resist retention. more power consumption equals less of an ability to resist retention. a Simple thing to do would be to set the power saving mode on your set. This way, the set consumes less power losin just the slightest amount of brightness (model dependant). Try it on your set(s) to see what kind of pictorial difference it makes. Again, the ISFccc calibration will also save power, so combining the two is usually Ideal, so long as you let your calibrater know beforehand that you'd like it set with the energy saver mode turned on.
Picture orbiters will move the picture unnoticibly 1-4 pixels, simply to prvent the information (RGB) from sitting on one pixel for too long. In movies, for example, there may be one particular area of the screen that has more of one color than other parts of the screen for the entire lngth of the film. The orbiter prevents retention in this way. Also, newscasting logod and gaming icons can also be left unretained if the orbiter is set. Basically, set your orbiter to ON. If it has more than one mode (like on the LG moedls), set it to the most extreme mode to prevent retention.
From my research and years of experience developing and calibrating/working on plasmas, I have found the whitewash or screen savers to be saved as a last desperate measure, for retention that does not simply go away with the next programme you watch. This IS NOT something you should be doing on a consistant basis, as a whitewash usually consists of a pure white screen, or a black screen with a white bar scrolling. white is the colour that takes the most energy to create, so yur set will be consuming huge amounts of power (maximum rated power in wattage is located on back of panel, and YES, it will consume that) and your set will rum extremely hot (I clocked 210F on my Pioneer 5080, whicj usually runs at 77F). Again, DO NOT use whitewash on a consitant basis, as you jeapordize the life and performance of your set!
I hope this helps, as it has taken about fifteen years to gather the development research and actual lab experiments.
Best of luck,