Gitlab had a long downtime because the backup was huge and on the other side of the country. The backup server was on a low speed network.
https://www.arcserve.com/blog/lessons-learned-gitlabs-massiv...
How much money would you lose if you were down for one week? How many customer would you lose?
How much credibility would you lose?
For my peace of mind, I can't afford a spof when I know one lingering.
How long does it take to try it? A day?
Well then try it, either it'll work flawlessly on the first try, either you'll learn that the backup you have doesn't include logins, password and the security configuration that goes with it. Or that the dump you took lost some data because it wasn't in the right encoding.
Or the tape drive you're using need specific drivers that aren't available on the web anymore because the company website's closed.
... This is a work of fiction. Any similarity to actual events might be purely coincidental...