Thanks for this, quite useful.

There's also more discussion in [1], linked from there, which contains perspective from real memory model experts. I think it's fair to say they're skeptical of the proposal. In particular, they've debunked the SC-DRF claim, which seemed fishy to me, but I didn't want to say anything before gathering more evidence.

[1]: https://discourse.llvm.org/t/rfc-strengthen-relaxed-atomics-...