Thanks for your examples.
To be honest, I never thought the lack of stability of clip-path animations was in any way related to GSAP. In fact, I’ve already used the AttrPlugin to achieve such animations. What I’ve witnessed on some projects, however, is crazy unwanted behaviors from the browsers themselves. Your first pen, for instance, is pretty janky in desktop Safari on a retina display. I don't blame GSAP at all, I know this is on Safari.
As for Chrome, when I say I’ve witnessed crazy behaviors, I do mean crazy behaviors:
This, for instance, is how I saw Chrome handled a particular SVG-based clip-path animation a few months ago.
The bits of content you see on the right-hand side, by the way, belonged to another tab I had just closed.
As you said, clip-path is still listed as experimental, and I came to the conclusion that it was for a good reason.