Automated test restores
I'm sticking with the legacy format for now for several reasons: 1) It doesn't support hybrid backups, and we have external drives deployed at each site for faster restores if needed. 2) The new format isn't available with VM servers, and we want all our clients to have the same backup configurations for easier management. 3) We only want 3 months' worth of backups, so GFS feels like overkill.
All of our backups are image-based, so I don't know if the dummy file idea would work.
My major concern driving the test restores is restoration failures. I worry that an msp360 update, bucket change, API issue, settings change, Windows update, etc could break a backup configuration. It helps me sleep at night knowing that the backups are bootable if needed. On top of that, industry best practices say to regularly test your backups.