"In IPv6 there is no NAT; therefore an IPv6-network will never be as secure as my IPv4 network. I don’t want my security risk to increase!"

NAT hides the network topology behind the device to the global network. In some cases this indeed contributes to security, but NAT was never intended to be a security measure. The idea of NAT as a security measure is fed by the issue that NAT devices are often running a firewall. Just using firewalls - without NAT – is possible in IPv6 as well as in IPv4. It should be noted that NAT causes many problems with protocols that have IP addresses embedded in their traffic (e.g. FTP) and this may even complicate security-management.