NAT demonstrably does not work fine. We have piles of ugly hacks (STUN, etc) that exist only because NAT does. If you really want to keep NAT then nothing stops

NAT demonstrably does not work fine. We have piles of ugly hacks (STUN, etc) that exist only because NAT does. If you really want to keep NAT then nothing stops you from running it on IPv6, but the rest of us shouldn't suffer because of your network design goals.