It doesn't sound as if this is going to turn the router into a mere straight PPPoE-speaking _modem_. Damn.
But I wonder if this might let me use a PPPoE client, such as my trusty Firebrick, to connect _through_ the device to AA's PPP/L2TP LNS? If so, then I could get IPv6 working. I would still need NAT as I don't have enough additional IPv4 addresses lying around.