[izzymiller]

just a data point: Hex we built a .yaml based import/export for our notebooks, more than partially to make it friendlier to work with git (also partially because as we added new features it became harder to express custom cell types in .ipynb).

We still support ipynb import/export, but using yaml for our internal representation of notebooks has made it hugely easier to do human-readable diffs and makes git operations way easier. (https://hex.tech/blog/github-sync/)