Adding vfs objects = btrfs to a btrfs formatted SMB share allows copy-on-write (i.e. instant) copies to be done using windows explorer (on windows 8/server2012 or newer) using Samba's server side copy functionality, obviously as long as the copy is done on the same filesystem, e.g., from cache to cache, disk1 to disk1, etc, this would allow for example to very quickly and easily backup a vdisk before any significant change without dropping to the CLI.
Alternatively allow the user to add specific vfs objects to any share using the GUI.