thanks for a good thread on the 768p vs 1080p display headache. I'm still trying to decide on what to get. I have to admit that I didn't read all the replies yet, but my impression so far is that too much focus is put on when you are actually noticing the pixel grid. If you do notice the pixel grid, you are sitting about half the distance from the display that you should be sitting. A pixelated image can only guarantee true contrast reproduction when image details are not smaller than 2x2 pixels.
What I am rather certain about, is that a 1080i image source is the main bottleneck. From the marketing department point of view, it's a minor detail to convert 1080i sources to display perfectly on an 1080p panel. If you ask the engineers, they will tell you that 1080i is very close to 540p, and not at all anything like 1080p. Displays treat the 1080i source very similar to a 540p source, because it's not much more that can be done...
In other words, a 720p source contains higher resolution than a 1080i source, and a 768p display have better native pixel resolution than both those sources. That means 1080p displays won't help at all for these sources. Moving closer to the screen, blur or artifacts introduced by image scaling algorithms will be visible long before you start noticing the pixel grid.
The only reason I have for considering a 1080p display right now is for use with a PC. Then I can perfectly match the source resolution to the display pixel grid, getting an exact pixel-to-pixel mapping between source and display. I honestly don't see any other way of taking benefit from 1080p displays over 768p displays right now.