Thanks for writing these updates, Raph - back in 2019, your early piet-gpu blog posts helped to reignite my interest in 2D rendering. I recently learned that you also invented Cairo's trapezoidal-coverage algorithm, which was my original introduction to anti-aliased 2D rendering ten years ago!
Over the last few weeks, this interest has finally spiralled into an attempt to develop a renderer of my own. I've come up with a design which seems promising, but I do have one question for which I haven't yet found a good answer:
It seems to be common wisdom that 16xMSAA has unacceptable quality for 2D rendering. In practice, though, I'm struggling to find any test-cases where I can differentiate 16xMSAA from 256-shade analytical AA with the naked eye. The only exception has been fine strokes (e.g. downscaled text, or the whiskers on this Ghostscript tiger [0]), which tend to "shimmer" or "sparkle" as they move. Does MSAA have any other common failure modes that I should be aware of?