> i want rsync --del, except, not within any dest side mounts.  sort of
> reminiscent of -x, but on the dest side.  anyone know the trick?

-x, --one-file-system
               This tells rsync to avoid crossing a  filesystem  boundary  when
               recursing.   This  does  not limit the user’s ability to specify
               items to copy from multiple filesystems, just rsync’s  recursion
               through the hierarchy of each directory that the user specified,
               and also the analogous recursion on the  receiving  side  during
               deletion.

well maybe it does do what i want.