Picking the wrong issues to care about
I have a rMBP with an LG screen and absolutely love it. Have done extensive testing based on this forum and other forums, and have had my machine for several weeks with Adobe and FCP work.
From what I have heard in the manufacturing world, was that Apple begun producing the rMBP back in February 2012 and at the same time LG was having troubles with quality consistency(read articles regarding LG and Retina iPad) and similar issues, and that by June/July the line was up and has sustained quality and consistency.(FYI: I work in China and besides design work, do QC management for smaller producers) so this situation is normal and unfortunate. Later builds should have no quality issues with their samsung or LG display. my unit was built in August.
More Important to me was the manufacturer of the Hard Drive, I find Toshiba HD products to be utter crap, I have had 4 HD failures in my Mid-2009 15" MBP, three which were replaced under Applecare with Toshiba HD, these failures all happened in the last 8 months of the warranty and my initial drive was a Samsung. So I was ecstatic to find that my machine has Samsung Flash Memory with there controller and more, which has shown better performance in cross testing between similar Toshiba and Samsung.
My machine is also free from any other defects, problems and is breathing fire in terms of performance, it is also very quiet even in heavy workloads(I have heard varied reports of louder and/or hotter machines) and my machine is also not hot at all even when rendering FCP projects.
So to future buyers of the rMBP, would I recommend it, absolutely, and i would be more concerned about the HD, the sound and the heat, than i would be about the screen, especially if you are looking to buy it now, I would watch out for older inventory unless you are a Samsungphile and absolutely think their screen is better. There is always a tradeoff, however, I would certainly recommend buying Applecare for this machine, it always pays off.