Very interesting! I hadn’t seen that thread, nor much else (from a cursory search) that indicated HLG had much traction.
HLG is still new to me, and I fully intend to experiment further before settling on a Standard Operating Procedure for my own uses. Dialing back exposure does seem to be backed by theory, indeed.
I also wonder, but haven’t yet looked into, to what extent Apple has done their usual thing of taking a standard and adjusting it as they see fit. In other words, what’s theoretically ideal may not always yield the best results on Apple hardware using Apple software, simply because they “think different”.
As much as -1.36 EV certainly takes some of the “pop” out, for better and worse. SDR compatibility takes a practical hit in the sense that the SDR representation appears much darker compared to regular SDR material in the Photos library. As long as there are SDR screens involved, I’d ideally like a version that works reasonably well in both SDR and HDR.
And yes, AVIF works equally well.