I don't think Verizon has turned on IPv6 yet for FIOS, so nothing is going to happen enabling it on the router. The last firmware push for Rev I gave us IPv6 capability but VZ hasn't started running IPv6.
Why have they started running IPv6 with IPv4 (dual stack) ? Last I heard/read, it was to start 3Q 2012 for non static IPs.
It was SUPPOSED to start in Q3 based on Verizon's last memo they provided... but it didn't, and no further update/guidance has been provided as to when it will start, or what the reason for the delay is.