There's a feature that could speed up time. Could it be possible to create a `file mapping feature' ? Namely, if a file to be rsync'ed doesn't exist on the receiving side, give a rule to try to obtain a file that should be very similar, and try to use that file to obtain the checksums. Assuming the use of --delete-after, this could be useful to speed up the synchronization of cvs repositories, where files tend to move between the Attic/ and the main directory....