All mentioned programs like WebDrive, FtpDrive etc have one single problem. They are usually not visible in backup programs as they do not appear as normal
Removable drive. So programs like Symantec Exec Backup 2010, Symantec Exec Backup 2010 System Recovery simply don't see it (even thou it is shown in Windows Explorer).
I've tested those programs and this was the main problem (those programs didn't see it the same way as Windows Explorer does) as i needed the ftp mount letter to have backup moved directly to ftp drive.
However I did find nice program that backup programs seems to
see it. I've not yet tested how backup will work directly to that drive but I do have good feeling about this (at least programs see it). Without further ado FtpUse is your man! :-)