For ArchLinux, I've seen this package surface:
openssh-xattr
As it seems a patched openssh that adds xattr facilities to the sftp ssh internal server. What's going on with this patch? Will it arrive on Linux any time soon? (Doesn't look like it will, see)
This would go upstream into sshfs-xattr... that's why I am interested.
Besides maturing the codebase, devs are adding features to sshfs, for example a recent addition is "a real statfs()", added when the openssh internal FTP server started to support that. But xattribs support in openssh is not on the horizon.
So the only solution is to use a patched pair of sshfs and openssh, as suggested by this ArchLinux effort. Or looking for different software packages, like perlsshfs, a recent release on cpan I've just found that tries to overcome sshfs' xattr limitations.