For stateful systems, tests named after setup details often get weakened over time. Tests named after the claim they are trying to falsify are harder to water down.
The part I’d be most interested in is how well this works for business invariants like idempotent posting, no lost acknowledgements and recovery after partial failure.
I agree with this. Moving the git repo is easy, moving the whole project surface is the hard part.
Issues, releases, CI, docs, security advisories, search and discoverability all tend to get coupled to GitHub over time.
For open-source projects, I like the idea of self-hosted as the source of truth, but still keeping a read-only GitHub mirror so people can actually find it.