After spending some time working on IPv6 using the MikroTik, I thought I would expand my horizons and suss out other networking devices that might lend themselves to IPv6 connectivity… initially with tunnels, but then also as a directly connected device.
A FortiGate 60B looked like a good place to start.
There is a lot of documentation on the web about where to start and how to get going, but nothing seems to be up-to-date with respect to the latest version of FortiOS 4.2. You can find the best guide, minus the updates, here: http://www.sixxs.net/wiki/Fortigate
The instructions for 3.00MR7 work OK for FortiOS 4.2.
Once configured, the tunnel came up without a hitch and IPv6 was working via the FortiGate.
The UI is a little different with IPv6 and not everything appears in the GUI as you would hope, so rely on the CLI as much as possible!