I think the G25 is superior quality to the 550.
However, I do believe the additional 4" makes a noticeable difference.
Hometheatermag.com has reviewed a G25 and kept it on for over 1000 hours and has shown no loss of black levels in their controlled environment (variables are constant for higher accuracy).
However, I believe floating blacks may be more of an issue than the rising blacks in panny's.
I am looking at purchasing a Samsung C6400 plasma myself (costco)
However, I do believe the additional 4" makes a noticeable difference.
Hometheatermag.com has reviewed a G25 and kept it on for over 1000 hours and has shown no loss of black levels in their controlled environment (variables are constant for higher accuracy).
However, I believe floating blacks may be more of an issue than the rising blacks in panny's.
I am looking at purchasing a Samsung C6400 plasma myself (costco)