Thanks for that - it looks like they may be using a revised Samsung panel. In my 2012 Retina MacBook Pro the screen model is LSN154YL01001, although the only difference is the final 001 is replaced with A01 which perhaps wouldn't suggest a large change.
Maybe the "A" is for Apple, a batch with more strict quality control
Another question for OP: Is it possible to run OpenCL on both GPU:s simultaneously?
Also, thanks for your time doing this review!