I posted on this discussion quite a bit back in the July/August 2012 timeframe. I was a retina display owner with an LG display experiencing the burn in issue. At the time my stated intentions were to wait a few months to give Apple some time to come up with a coherent solution to the problem before going to the Apple store and asking for a fix. As it turned out, I never bothered because although my display clearly had image retention, it occurred in situations so unusual and unimportant to me (I use a colorful desktop background normally and the only time I ever noticed IR was when using a flat Windows 7 background in Virtualbox). I still figured that eventually I'd ask for a fix before my one year warraty ran out but never did.
Then about a month ago I started having the 'flickering display' issue that I think other people have reported as well. Lots of window fragments jumping around on the screen and flickering; this would occur for a few minutes at a time and then go away for a couple of hours. So for this issue I did bring the laptop to the Apple store and request a fix, because this was a fault that I could not overlook as easily.
While at the Apple store describing the flickering problem I also mentioned the image retention and asked them to put on the work order to check it. That was all I said and they did note it on the work order.
Five days later I got my laptop back and the work order said that they replaced a logic board to fix the flickering and also replaced the display to fix image retention. So I checked the display type using the ioreg command and lo and behold - I got a Samsung. I didn't even push hard for it; I just asked that they look at it while they were fixing the flickering issue.
So I'm pretty pleased that it all went as I had hoped - waiting for Apple to come up with a coherent response seems to have worked in my case, where I just had to mention the issue at the Apple store, not push hard, and I got a Samsung replacement.
I can't really notice any difference in the white level with this compared to my LG but I don't have them side by side. And I've got no dead pixels to note, and of course, no image retention with the Samsung. I'm very satisfied with Apple's response to my issue and the results. I think there is no reason that they shouldn't provide the same level of service to everyone if that's not already happening (I haven't been back to this discussion in months so I haven't kept up on the status of this issue).
Best of luck everyone!