Do you run virtualization in your DC? If you do, is IPv6 only inside VM context or you also use it as a transport (i.e. switches see IPv6 packets)?
This means packets will be dropped but that's not a bad thing when you have other layers taking care of retransmission. So routers then don't have to spend a lot of time chopping packets up and can just either shift packets faster or drop them telling the sender to slow down.
The other advantage I hope we see enabled is multicast. All these streaming services could massively reduce their bandwidth usage if the Internet allowed multicasts.