/cf size vs. rrd data
The GUI notes, when backing up, that including the rrd data the config file might > nMB in size. What's not clear is that /cf might be way to small to ever restore that file (mine is 1.7MB on embedded, my backup was 3.1MB). I know how to edit the XML, but not everybody should be expected to.
In general, providing a backup that can't be restored is poor form, so perhaps if it can be seen that the rrd data is larger than /cf, the GUI could note that it can't be restored on this machine, or just make it impossible to include it if it would cause such a failure.