Ok for all those wondering what this issue looks like, here is the best I can come up with...
Ignore the coloured 'moire' patterns which is just the result of picking up the RGB crystals, you can't see them with the naked eye. The screen is also clearer and brighter than this image shows.
However, it does go a long way to illustrating the un-evenness of the backlight, even if it is exaggerated in the photo (not artificially, the camera just saw it that way). It also shows a slight discolouration.
See what you think!
http://www.spacerecordings.co.uk/LEDscreen.jpg
thats what mine looked like aswell... uneven backlight on the bottom half, and with the warmer LED giving out slightly yellowish lighting, its pretty much what this whole yellow LCD problem is. Its not that obvious but its noticeable, its annoying when your reading something and it gets darker towards the bottom.
I've returned mine after one replacement. I'll try again in a month or two.
and whats that red dot on near the middle? is that the camera or a stuck pixel?