Personally I think that Google Group is the way to go and it can act
as an excellent forum. I've used Invision before and I'm aware that
it's an excellent system, however, the google group is already
integrated with the NRTL Google account. This makes it easier for
anyone to use the account and have the ability to moderate with out
the need for separate logins or accounts with different companies.
By keeping the forum to the google group we can make it easy for the
people after us to come in and take care of the group with minimal
transition time. I chose this as the forum after looking long and
hard into some other things, PHPBB, Invision, PBWiki.....etc. This
one required almost no learning curve and it had more than enough
features to integrate into the account. There are still some that we
aren't using but we do have the ability to use, an example would be
integrating the calender into the forum, which is also google account
based.