Those registry settings were very helpful for me because I do most backups or restores for databases using T-SQL; but this one time I got lazy and decide to use the GUI interface and got following error when trying to enter the file name.
TITLE: Locate Backup File – ServerName
Cannot access the specified path or file on the server. Verify that you have the necessary security privileges and that the path or file exists.
If you know that the service account can access a specific file, type in the full path for the file in the File Name control in the Locate dialog box.
So please be cautious when changing the registry settings; the GUI interface cannot work with UNC.