Have been working on a design for [[design/exporting_trees_to_special_remotes]].
As well as being handy for publishing scientific data sets out of git-annex
repositories, that covers long-requested features like
[[todo/dumb, unsafe, human-readable_backend]].

I had not been optimistic about such requests, which seemed half-baked, but
Yoh came up with idea of exporting a git treeish, and remembering the last
exported treeish so a subsequent export can be done incrementally, and can
fully sync the exported tree.

Please take a look at the design if you've wanted to use git-annex for some
sort of tree export before, and see if it meets your needs.