On the HC2 I use snapper to create snapshots of the OS filesystem (btrfs) before and after an update. Snapshots are created automatically by apt-get. Seems to work fine, though I have not tested a roll back, yet.
Problem comes with the backup plugin. In the backup of fsarchiver all snapshots are included. Each of them with the size of the complete OS.
Any chance to exclude the snapshots from the backup?
In case of a dead SD-card I would use the latest backup from the plugin.
In case of an update going wrong I would use the last "pre" snapshot. So I think I do not need a backup of the snapshot history.