I'll preface this by saying that the following observations are entirely my own based on my visual perceptions so be kind. After having an first generation 40" Sony Z set for 3 years, I decided that it was time to upgrade. Because of the LCD's panel uneveness, clouding, variable black levels and poor field of vision, I figured that it was time to look at a Plasma set. I bought a 46GT24 from Costco a couple of months ago and while it is a very good set, I felt that a 50" with the newer panel would be worth looking at. The 50ST30 arrived this past Friday and I'm still experimenting with the video settings. The combination of the larger panel and the thinner frame had more impact on the feeling of screen size than I would have thought when compared to the 46GT24. Before making a final decision to return the GT24 to Costco, I wanted to do some kind of A-B comparison between the two sets. I finally did that yesterday. While this certainly wasn't a comprehensive test, here are my observations. .
1. First test: HD Cable. DVR'ed parts of several HD programs and played them back on both sets via HDMI. Custom mode on the ST is better and easier to calibrate than the GT's and is more neutral to the eye. Overall image is close with maybe a mild edge for the ST but I was right about the grain. The ST exhibits less graininess than the GT does. Possibly that's the improved processing chips at work.
2. Second test: SD cable. Absolutely better on the ST. Less noise and blockiness on 480i at 4:3 and in Just mode. The new LSI chips appear to rule here.
3. Third test: SDVD. Put on the second disc of Return of the King where the Corsairs are boarded by the ghost army. Again the ST does a better job of upscaling to 1080P. The image is smoother, has less noise and fewer jaggies.
4. Last test Blu-ray: Harry Potter #4. The GT did a very good job in Custom and THX modes but frankly, the ST30 in Custom mode just looked better to me. The Warm 1 setting especially looked more balanced. The image was a bit brighter and blacks stood out a bit more. It was just a more pleasing picture. Of course the larger screen is a plus.
5. The THX mode on the GT is, I think, better than the Cinema mode on the ST but the Custom mode apears to be where the ST will live and breathe.
So that's a cursory comparison between the two Pannys currently in my possession (which better be down to one very soon or I'll be moving one set into the garage because, per the wife's fury, that's where I'll be living