I ordered an iPad Mini 4 strictly for flying the P4P, and although I think it's the perfect size, as well as being bright enough with an average sunshade, after a FW update, my CPU could not keep up and I get green screens and screen blackouts, even after clearing my cache, and turning off video caching during flights. I've since switched to an iPad 10.5" Pro, and am not having those issues, although it's somewhat bulky and imbalanced.
I just sold my Mini4. It wasn’t up to the task, going back a few updates. I thought it was Go4 but it turned out to be the m4. My iPhone 8+ is perfect but to small for my eyes. Love my Crystalsky 7.85.