Things are going well so far using a filesystem as a PIM. One odd observation, though, about OS X.
If I create a symlink from a shell, it comes up as an alias in Finder. But if I create an alias in Finder, it doesn't look like a symlink from the shell (it's an empty file but there's no display of the target).
There may be broken links to media on this page. I'm still in the process of migrating them over.