Ed Horley of Howfunky.com comments:
I’ve written previous posts on NPTv6 but it seems I didn’t do a particularly good job explaining the different between NPTv6 and NAT66 and there is still a lot of confusion understanding what the actual difference is between the two. While both are doing network translation they are doing it differently.
Ed does a great job of differentiating address translation from prefix translation in IPv6. One of these has a future, the other is going to cause no end of pain.