The backup module needs to be outside the “www” pathe for security reasons and only the backup/backup folder should be linked into the Modules folder, so (for example) the path to backup_view.php should be emoncms/Modules/backup/backup_view.php not emoncms/Modules/backup/backup/backup_view.php.
I use the usefulscripts because I’m used to that and feel I have more control.
Have you tried the emoncms/sync module? Just to muddy the waters a bit with another option
Are you trying to do an incremental backup, maintain a sync’d copy or migrate across setups?
That would sound like a task for the backup module, which I’ve never tried. @Paul did some work on this topic using rsync (if I recall correctly) but I don’t know if that is still active.