I tried out (have 2 mybook live with 3 TB each) the WD backup tool.
It uses windows style fileshares to do this: the receiving my book offers a windows (SAMBA in fact, it is linux) fileshare to the mybook wanting to backup.
consequently, windows filename restrictions are enforced.
names with for example characters like " : / | < > * % and more, will NOT be backed up.
see for more info here:
if you are like me a linux/Unix user, and want to backup your linux/Unix files, you could use the sftp command to get your files on the boxes.
For syncing the two I use the rsync command available on the mybook (requires you to use the command line, do not try if you do not know unix / linux )
You could also use filezilla or so, but that’s a little inefficient and does not work unattended…