I received an invitation - it really makes you wonder at the seemingly randomness of who is invited! We too have done two ABDs, but are booked, like Bobo912 on a Tauck Bridges tour this summer.
After a quick look at "My Family Adventure", I decided to take a "wait and see" attitude to see how it evolves. I wasn't sure what it would provide me that I couldn't get more directly and un-filtered from the disboards. So, the link is in my saved email and I'll go back from time to time.
It is interesting the various ways these on-line forums evolve for various groups. While there is tons of info on the disboards for ABD, there is virtually nothing on Facebook. It is the opposite for Tauck - many postings on Facebook (but none of substance really, just saying how great such and such trip was), but very little on their "Ask & Share" area, where people might answer specific questions or post trip reports. I don't think it's just because the disboards is independent - I think it's more a different target market. My perception is that the AbD'ers are a younger group for the most part than the Tauck folks, therefore, more apt to desire information via the internet. Maybe?