We started with IPv6 on 2 January 2011.  We knew that there was a major change in the protocols and that it would be coming soon down the road.  We talked to our ISP and they were not offering IPv6, so we acquired some tunnels.  For hosting, we found that NAT worked well for us on IPv6.  We shortly thereafter acquired a network range and migrated away from NAT.  However, for testing, we do still encourage the IPv6 rate for fc00::/7 to help you out on learning IPv6 internally.  NAT does take some CPU and RAM, so you might need to take that into consideration if you want to adamantly use it on your network.