Its the only service that stops me being able to run test machines ipv6 only. Everything else I need supports ipv6 already. And hey they have loads of people, surely one of them is interested...
Just install NAT64 on the network so that they can reach ipv4 if needed
As far as I can see I would still need to run ipv4 NAT in order to get ipv4 addresses for NAT64, so it doesnt really seem worth it.
One per network is fine though, you can run thousands of hosts behind one ipv4 in nat64