List of companies is linked above - looking quickly I'm going to guess less than 1/2 -- maybe 1/3 are both 90 and SLA. I think SLA offers open meetings for the first time for anyone who wants to join but that would be up to them.
I saw Jerry, Moira, ISM, John Hoyt, Darcy (websitepipeline) at the Summit event. I suspect there are more that I didn't see. I don't know how often they got to the meetings.