I have a CR1000A, currently running 3.1.0.22. I upgraded from a G1100 (which also had IPv6 enabled) a few months ago, and have found some bugs with the new device.
On the G1100, I was able to set up a static route that sends a second /64 in the /56 we are allocated to another device on my network so that I had a second subnet. i.e. the main prefix would be :1200::/56, the router would assign itself :1200::/64 for the LAN, :12ff::/64 for the WAN, and I manually allocated :1201::/64 for the other subnet. Apply a static route for :1201::/64 with a next hop of :1200::2 (the address I gave the other device that hosts that subnet), and a companion default route on that device, and I had IPv6 to the outside from the :1201 subnet.
On the CR1000A, I tried to do the same thing, and found 2 bugs:
1) The static route is not persistent across reboots. Apply the route, and you can ping between subnets. Reboot, and you can't, at least until you remove it and re-apply it in the UI.
2) the router won't actually route traffic externally from the second subnet. i.e. even when I can ping from :1201::2 to :1200::1 (the router is routing traffic between them locally) I cannot ping anything external from 1201::2 or vice versa.
Note that none of this would be an issue if the router either supported DHCP-PD requests from downstream devices so that I could just request a /64 out of the /56, or it actually used a separate subnet for the built-in guestnet, since the whole reason I have a second subnet is for separation of guest traffic.
This is being cross-posted on DSLreports since I'm not sure where the most appropriate people in VZ IPv6-land hang out.