"IPv6 security is less mature than IPv4, and there is less experience with IPv6 security and reliability issues. So migrating to IPv6 might lower my security and reliability level."

A new technology has the drawback of lacking experience and best practices as far as operation of the technology is concerned. This is also true for IPv6, especially since the IPv6 protocol has more functionality than IPv4, and is therefore more complex. For this reason network operators and technicians need to start experimenting with IPv6 right now. In this way they will gain experience and at least circumvent currently known security pitfalls.