In the delaysmudge branch, I've implemented the delayed worktree update in the post-merge/post-checkout hooks for v6. It works very well!

In particular, with annex.thin set, checking out a branch containing a huge unlocked file does a fast hard link to the file.

Remaining problem before merging that is, how to get the new hooks installed? Of course git annex init and git annex upgrade install them, but I know plenty of people have v6 repositories already, without those hooks.

So, would it be better to bump up to v7 and install the hooks on that upgrade, or stay on v6 and say that it was, after all, experimental up until now, and so the minor bother of needing to run git annex init in existing v6 repositories is acceptable? If the version is bumped to v7, that will cause some pain for users of older versions of git-annex that won't support it, but those old versions also have pretty big gaps in their support for v6. I'm undecided, but leaning toward v7, even though it will also mean a lot of work to update all the documentation, as well as needing changes to projects like datalad that use git-annex. Feedback on this decision is welcomed below...