]Changing the Documents location will not change the locations of the iTunes Mobile Backups, as they are not saved there.
It's possible to change the location of the backup by creating a Symbolic Link on that folder, in Unix/Linux world. It would be done using a command similar to
ln -s /Where/I/want/to/put/the/backups/ ~/Library/Application Support/MobileSync/Backup
, after having moved the folder (otherwise, it will remain in place and inaccessible unless you remove the symbolic link.
The same seems to be able to be done under Windows using an NTFS junction. You would need to use the following tool: http://technet.microsoft.com/en-us/sysinternals/bb896768.aspx
After installing (or unzipping) it, you would go in the command prompt, and type the following command (replacing %username% by your real username):
- Windows XP
junction W:\here\you\want\to\backup "C:\Documents and Settings\%username%\Application Data\Apple Computer\Mobile Sync\Backup"
- Windows Vista/7
Administrator rights may be required to perform this task under Windows Vista/7.
junction W:\here\you\want\to\backup "C:\Users\%username%\AppData\Roaming\Apple Computer\MobileSync\Backup\"