When doing a quick refine mask in Photo I notice there is some blockiness. I refined a pink hair over black photo (masked on white background here) and it looked ok at 100% but some detail seemed fuzzy. I magnified a great deal and found out why- see attached.
I ran this comparison test again. This time please see before and after for both Photoshop CC 2017 and Photo beta 4. I had to manually adjust to get them both at 600% magnification, which, to be fair, is really nitpicking at this magnification. But still there is a very slight artifacting that these quadrilles are contributing to - otherwise Photo Beta 4 is a dramatic improvement over previous versions of Photo.