Re: I've said it before and I'll say it again
Have and Upvote then, as nothing in your post was cheerleading v6, and your comments on the firewall rules are on point. IPv6 isn't evil. It needs a few things fixed, and for people to stop shoving it down down other people's throats without listening to them. You did none of those things in your post.
The only equipment manufacturers that still have real IPv6 issues are at the very bottom end. That gear should not be connected to the internet by anyone, ever.