Update guys.
I just received my latest and last ditch replacement today and I just can't believe what the terminal command tells me... IT'S A SAMSUNG!!!!
After 4 replacements / 5 rMBPs this one finally came with the one thing I had wanted all the way through this process. I had practically given up hope of ever getting one of these seemingly elusive displays.
I've only had a very quick 5 minute play with this replacement as I'm snowed under at work but I just had to check as soon as the replacement was delivered. The screen is very sharp, bright and white, I can see that much. There does seem to be a little unevenness as some people have mentioned, however, it is in comparing the right hand side to the left where the right side is (very) slightly yellower than the left.
Apart from this, there doesn't appear to be any dead pixels or mura, no creaks and no uneven backlighting either on the screen or the keyboard.
Everything taken into consideration, this one's a keeper for me unless I can see anything else under a darker light that bothers me. If for any reason at all I decide to send this back then it's a refund until the 2nd generation comes out next year but I wouldn't like to hedge a bet that the screens on these will be any better than the 1st generation. This may be especially true if Samsung and Apple fall out completely and we're stuck with LG / Sharp as a supplier. Based on this I'd rather stick with one that does have a Samsung screen and not have to potentially play the lottery again next year.
For reference, I've just looked up the serial number and it comes up as week 44 on appleserialnumberinfo.com with a configuration of 2.6 / 16 / 512.
I certainly hope that Samsung will be used more frequently for the rest of you in new builds and that this isn't just another one week wonder like we had with week 39 / 40.