I had a launch day iPhone 6 Plus in Gold 128 GB. Had some cosmetic defects, thought of getting replaced through the Genius bar, but opted not to, since if you do a get a replacement unit, you can't do a return (of course some apple employee can make an exception).
So today at 6 pm, I checked istocknow.com. It showed that the Gold iPhone 6 Plus 128 GB was in stock. So I went ahead and went to the Apple store and got my iPhone 6 Plus exchanged. Very happy. No yellow tints, no cosmetic defects, no dead pixel, no light bleed. Everything is just perfect. But of course, it extended my 14 day return again.