[throw0101d]

> For example, in IPv4 each host has one local net address, and the gateway uses NAT to let it speak with the Internet. Simple and clean.

If you think NAT is "simple and clean", you may wish to investigate STUN/TURN/ICE. An entire stack of protocols (and accompanying infrastructure) had to be invented to deal with NAT.

Heaven help you if your ISP uses CG-NAT.

[cyberax]

I can type entire SIP handshakes from memory. And by now I'm convinced that STUN/TURN are a superior solution to IPv6, even with CGNAT.

Others agree with me. Don't believe me? Try to find a SIP provider in the US that has IPv6 connectivity. Go on. Try it.