As others have said, all 43u's are nearly identical, besides screen size, obviously.
See the 32D43U thread for more info.
I have a 32D43U and I'm very happy with it. It has good blacks for the price range and the motion blue (6ms response time; 8 ms is typical) is so minimal I don't even notice it. Plus I haven't seen any bad pixels at all.
It has a couple annoying things, but they aren't deal breakers to me:
1. You can't change aspect ratios at all in HD.
2. The OPC (optical picture control) that automatically changes the backlight depending on ambient light doesn't work very well. It isn't bright enough for most people. (You can turn it off)
3. You can't fine tune the color temperature beyond the presets. The lowest setting makes whites a little too red and the second lowest makes whites a little too blue.
EDIT: I forget I posted in this thread already. Just add these comments to my other post. Sorry