@ - Make a PR whenever you think you have reached a good point. Things like PMC->SMC really shouldn’t be too hard for me to fix, even if you haven’t done them yet. It probably will take a while to review, as your changes sound pretty major, but it sounds like some good wins too. I’ll probably need some input from the Rendering Team as well.
I already had it on my list for 4.13 to look at cooking performance and tesselation for PMC, so I’m very interested to know what you find out there! Maybe we do one PR soon with the basics, and then a further one which are those changes later on.