I don't think you can do backup from Smart console, u can only backup system database from smart console.
One time I did the backup like this:
1. Putty to the Security Gate and run: Save configure
2. FTP to the appliance and download the save configure txt fille
3. Web login the appliance and go to maintenance-->System Backup, you can create backup from here and export down locally.
I tried to created a VM as SMS server and applied all the update and applied the Save configure file, then from the web login of new SMS, import the backup file and restore it. it successfully restored, however I encountered a lot of error and majorly because of the patches, it must be have exactly same patch applied as production system, then can be restored.
You can have a try and we can share experience