So the way I read it, if you want to opt in, you make the new changes they state in your yml. I didn’t and just hit upgrade to pull the new images and it worked fine. I don’t see any issues, but I’ll be glad if someone says I did it wrong.
I think it’s only breaking if you pull the new yml and don’t move your data.
Here’s the thing, you own the domain, set up what ever email alias you want and send it to your primary.