[backendanon]

IPv6 needs to die. IPv4 using NAT ensures a moderately high level of privacy. IPv6 with privacy extensions does not.

[basique]

IPv4+NAT still exposes your router's address, which is still problematic, no? If you want more privacy than that you can use a VPN, which should work on IPv6 too.

[allarm]

You need to use firewall in BOTH cases. You're blaming the protocol for completely unrelated reasons.