The thing that jumped out at me first is that the PK550 picks up much more glare than the G25. The G25 is probably the best plasma I have ever seen in that regard. With both sets turned off, the PK550’s screen might have been a tiny bit darker with the lights on; but the reflections were much more distracting. The slim PK550 seems to run hotter than the thicker G25, which seems to produce surprisingly little heat. With both sets on but with a black 0% input, the G25 subjectively has slightly darker blacks, and it’s blacks were more neutral in color than the PK550’s slightly greenish glow. The PK550 seemed to be more susceptible to image retention than the G25.
The PK550 has much smoother pans; the G25’s 48Hz mode has too much flicker in my opinion, so I never use it. That gave the PK550 the advantage in handling 1080P/24 Blu Ray motion. The PK550 had bolder colors than the G25, and had a harder edged look with more pop. The G25 looked less contrasty and a bit on the washed out side of neutral in comparison. The G25 had more visible shadow detail, but it was a bit too visible to be truly accurate. The G25 had a slightly greener tinge and paler look to fleshtones. If you are the type of videophile who routinely turns down the color saturation to make various sources more palatable, then the G25’s presentation would appeal more to you. On the other hand, lovers of rich and vibrant color tones would be more attracted to the PK550’s picture.
Because of the G25’s highly visible shadow detail, slightly higher light output capability, and superb resistance to reflections, I feel it would be an excellent choice for a brighter room. However, the PK550 has a more exciting and accurate image and would be a superb choice for a more light controlled environment.