Amarok That's part of the reason why it won't be a part of core, and will be so drop-in (if you enable it but then have to remove it, posts won't break since it's based on s9e textformatter). I'll also note that my extension includes a user preference setting where users can revert back to the simple editor.
Additionally, the changes needed for the editor driver system will also allow us to update to the latest version of mdarea, meaning that we should be getting full undo/redo support in the core editor, for anyone who prefers that typing experience.