Hasn't it been on by default since 8 or 7? Comcast supports it and it works as well or better than ipv4 for me. I would guess everyone using a managed Comcast

Hasn't it been on by default since 8 or 7? Comcast supports it and it works as well or better than ipv4 for me. I would guess everyone using a managed Comcast Gateway and Windows, or anyone on their Network who enabled it manually is running it by default.