Just throwing my experience in here for the record.
Bought an Air 2 from Staples which had a defective backlight: 50/50 split screen with one half being a good, bright neutral white and the other a delicate but distinct shade of pink. Drove me to endless distraction, as I'm mostly using the thing for books right now. Took it to the Apple Store.
There, I was given a replacement. To make a long story short, the replacement also had issues — still some pink tint, on the opposite side of the screen this time, extending from the top edge and fading out unevenly after app. 1-1/2 inches. The display was also noticeably dimmer, with fairly bad fading around 3 of the 4 edges.
I retrieved the original unit and took it back to Staples for an exchange. The third unit is completely free of any offensive tint, and while still not as bright as #1 and still having some fade along one side, is easily the best of the three.
Apple was, after some stiff persuasion, willing to offer me one more replacement if this one hadn't worked, but if it had come to down to four attempts I would have to say there are some serious issues with the Air 2 displays, and even having achieved what appears to be satisfaction I still think there may be a general problem here.