I've browsed through this and many other similar threads. Due to the premature death of my Samsung 27" 4:3 HDTV (less than 5 years old), I ended up the market for a big screen sooner than I thought.
Initially I was going for the HL-T5075S, but my wife and I were disappointed in the picture we saw in-store. It had major geometry issues with vertical and horizontal lines; it also showed strange shimmering with some high contrast white lines & text. This week the HL-T5076S had a pretty good sale, so I was deciding between that and a Sony 50A2020 for about the same money. Looking at the HL-Txx76S models in different stores, it seemed that most of them had what appeared to be acceptable geometry, with one of the 50" models looking really screwed up.
We got the HL-T5076S and set it up last night. The geometry seemed in the bottom 30% compared to in store models; horizontal lines seems to be tiled counter clockwise a few degrees. I measured about a .5" rise across the bottom & top, which is around 12-13mm. Certainly out of spec compared to Samsung's 7mm standard. What surprised me is that the horizontal lines are even warped in the center of the screen. However, the vertical lines all appear to be very straight. When watching 4:3 content with vertical lines, I could not measure a difference between ends.
I don't know if I would attribute these issues entirely to the TV frame. The sides seem quite strong, and I could not affect the image by applying pressure on the sides. Certainly the image tilting is not due to the top bezel. The curvature in the center of the screen may be due to slight screen bulging, but that doesn't go away by pulling on the top bezel.
In any case, my wife and I watched the DVD Wild Hogs on my Pansonic RP82 progressive scan DVD player, which some may remember as a classic, highly regarded 480p DVD player with a Faroudja (sp?) chip in it. I was completely stunned. The image was flawless. I have not even touched the colors on the set, but I did turn off DNIE and set the image mode from Dynamic to Standard. The colors are all so pure, accurate, and intense when they need to be. To our eyes this TV is *plenty* bright, and we even turned the brightness down below 50. You cannot see any pixels, and there is of course zero screen door effect. The black bars on top & bottom (probably 2.35:1 content) just blend in to the background.
This is when I realized why most people never return their sets; in normal viewing, especially movies with complex imagery, you will very rarely notice a problem. In either case, I didn't know how good DVD could look, so that was above my expectations.
I hooked up my Dish Network SD DVR via composite video. The image looked pretty bad; basically it looked very blurry, which is not the TV's fault. Then I hooked up the S-video, and it made an improvement. We like to view normal TV in 4:3 mode, and the geometry issues are obviously less severe on this setting. After 10 minutes or so we got used to the PQ and it is fine.
The last thing I tested was my GameCube with component video cables. Wow! Very very impressive. Sure you can see some of the pixel lines, but the screen is completely faithful in presentation. I left it on game mode, though the difference is not immediately obvious.
So all in all, I am very impressed with the TV. We could live with the geometry issues, but I just may swap it for a new one at Circuit City in a few days. I am not inclined to switch to the Sony A2020.