Hi Colin,
I installed 20H2 on my observatory computer without a problem. Of course, it's daytime so bad things won't show up until some evening. OTOH, I was totally up to date on all previous updates, so what might be a significant update process for some users was a brief download and quick install for me. (I rebooted twice, Eric ) The only thing I worried about was the update resetting the USB power management stuff back to a default "allow computer to turn off USB connections," but that didn't happen.
This update was not offered on my in-house desktop computer, so I'll have to wait and see. But there again, I'm totally up-to-date otherwise.
I hope all is well with you. Winter has come to our neck of the woods - it snowed very briefly yesterday but melted hitting the ground. Overnight temperatures this week are below zero (C).