> IPv4-with-more-bytes is not backwards compatible with IPv4
Neither is IPv6
> To get, basically, the same effect as moving to IPv6
The only thing that IPv6 solves which is of interest to 99.99% of the users is having more adressable space. The rest of IPv6 features are either things that nobody asked for, or things which are genuinely worst compared to IPv4.
I consider the mere fact of enabling IPv6 an unacceptable security risk, as I would now have to make sure my IPv4 and IPv6 firewall stack are perfectly mirroring each other. That would be trivial with IPv4-with-more-bytes, it's a nightmare with IPv6.
> I would now have to make sure my IPv4 and IPv6 firewall stack are perfectly mirroring each other.
You'd still have that in your IPv4-with-more-bytes, as you'll still probably end up running dual-stack to address those old-v4-only sites. Or you'd do the same with v6 and run a tunnel to translate those v4-only addresses to your v4-with-more-bytes. So you're in the same situation either way.
Neither is IPv6
> To get, basically, the same effect as moving to IPv6
The only thing that IPv6 solves which is of interest to 99.99% of the users is having more adressable space. The rest of IPv6 features are either things that nobody asked for, or things which are genuinely worst compared to IPv4.
I consider the mere fact of enabling IPv6 an unacceptable security risk, as I would now have to make sure my IPv4 and IPv6 firewall stack are perfectly mirroring each other. That would be trivial with IPv4-with-more-bytes, it's a nightmare with IPv6.