Hi all,
I just successfully restored a backup of my phone to a new phone and I wanted to share some of the particulars I learned in the process. It's understood that SeedVault has issues and the awesome devs of GOS are planning a replacement in the future. In the meantime, I hope this helps clarify how to use the built-in backup utility
All of these tips are just based on my experience. I may be wrong on some points, but after a lot of trial-and-error this worked for me.
Don't bother trying to use the utility to back up your user data. I never got this to work at all.
Go ahead and backup your apps. During the backup process, the utility threw some errors saying that some various apps could not be backed up for some reason. But then after restoring the backup to my new phone, all of my apps were there.
The restoration process cannot backup Google Play Store or Services for some reason. Once you get your new device up and running, install it from the App Store if you are going to use it, then proceed with restoring the backup.
Don't waste your time trying to backup to an external USB drive. I spent a lot of time troubleshooting the backup program, trying various drives with different file systems and it never worked. Instead, I ran the backup to my local storage, then copied the .SeedVaultAndroidBackup folder to an external drive using my laptop as an intermediary. I also like this option because you can format your backup drive with a journaled file system, in lieu of fat or exfat.
After the backup is safe, and you have your new device, go through all the steps to setup GOS on the new device. Skip right past the prompt to restore from a backup. Then copy all of your user data onto the new device, including the .SeedVaultAndroidBackup folder. Then go into Settings - System - Backup and restore the backup to your device.
All in all, the backup utility did save me a ton of time (versus starting over from scratch). It's not perfect - there were various accounts, settings, and preferences among various apps that did not survive the restore process. But that's fine, the bulk of the work is handled by the backup utility.
So don't rely on it 100%. But it actually does work fairly well, even better than the utility would lead you to believe.
Hope this helps some others avoid some headaches and wasted time