I did one return and repurchase through John Lewis, one swap through John Lewis, and three *aborted* Apple Store swaps (the genius saw the new one had the same problem as the current one and didn't complete the swap). So I've had three devices in my possession and inspected a total of six. I don't see a need to provide proof, not sure what the point is. Just looking for the more helpful members of the forum to let me know if flawless IPP screens really do exist. Thanks.
Not an iPad Pro, but I've had two iPhone 6's with dead pixels. The first one I just let go unrepaired (or swapped) for months before finally getting to an Apple Store for a replacement. The second one I type this reply on. I'm not even going to bother replacing it under AppleCare plus until just before it runs out in 2016.
I've never had a dead pixel on any of my other idevices (iPad 2, iPad mini, iPhone 3GS, 4, 4s and 5s) or Macs.