-file, meaning that the rsync algorithm can't extract the full amount of
-network reduction it might otherwise (since it does not yet try to sort
-data matches -- a future version may improve this).
+file, meaning that the rsync algorithm can't accomplish the full amount of
+network reduction it might be able to otherwise (since it does not yet try
+to sort data matches). One exception to this is if you combine the option
+with --backup, since rsync is smart enough to use the backup file as the
+basis file for the transfer.