First, thanks for the excellent plugin.
I haven't tried your development version yet, so maybe these suggestions are mute.
1 - Allow for a means of breaking up the backup snapshots. Set a max size for the snapshots and when you run the backup process it will make a collection of files no bigger than the max a person sets. On restore it runs through the sets of files to do the restoration. We've run into some issues with some hosts where the backup files are too big.
2 - Maybe add an in plugin restore option. We normally use Duplicator for migration and it's excellent for that. But the possibility of restoring a backup from with WordPress would be a nice added feature.