Ah, I must have previously installed it on this system and not remembered it. I’ll update.
The open question, IMO, is how we’d make this comparable to the built-in backup/restore. I’m pretty sure, by backing up everything in /etc/backup-data.d/*.include, we get all the same data, but there are probably other steps needed to get the configuration in a usable way.
Compared to the standard system, Duplicati lags in that it won’t handle SMB/NFS mounts. It can certainly back up to those locations, and maybe you could mount/unmount the shares using the run-script-before and run-script-after options, but it would be an added step. The big win in my book is how easy it is to set up the cloud backup (while it’s still encrypted, so Google et al can’t read your data).