Per Devahrudaya Raj's response, you can clone from lower to higher versions, but also remember you can manually clone anything you want. By going into SnapDrive and attaching to a LUN that resides in a SnapShot, SnapDrive will automatically create a FlexClone (provided you have it licensed). You can then use SQL to manually attach or upgrade, or downgrade whatever database files reside in that LUN (or set of LUNs if your .mdf and .ldf files are split up). Just remember, though, that if you manually attach to a SnapShot with SnapDrive, you will also need to manually detach from it otherwise the SnapShot will hang around forever likely messing with your retention policies. Scripting an action like this should be fairly easy with a combination of PowerShell and the SDCLI (SnapDrive command line interface).