Re: And what about BT and Virgin?
Some of the smaller ISPs have been at 100% deployment for a couple of years now. AAISP have as has IDNet.
I used to be with an Entanet reseller years ago, and got connected to Entanet's experimental service, and then after a hiatus, to their main service (on a different prefix). However that eventually failed when some lash-up kit they used for connections via BT 20C networks failed. I got fed up of waiting for them to fix it & moved to AAISP a couple of years ago. I very occasionally see v6 outages - there was one yesterday for a while - which I notice when, particularly, fonts.googleapis.com hangs (lots of websites seem to use this).
Naturally I'm all dual-stack here for all my hosts except for backward vendors such as the TV kit. It would be good to go v6 only but that needs a 6-to-4 proxy service somewhere for all the v4-only services out there that will never die, and I can't do it until all the v4-only kit here goes to recycling.