yeah - good point, my post was a bit obscure
here is the information that has been posted publicly which is a bit old (last year)
Things have changed a bit since then but no stats we can post publicly at this stage - hopefully at some point we'll write a nice white paper on the processes/systems.
Once you get up to this number of users it's not really important how many users you have but how they use the system, how active they are and what time-frames they use the system. From what I understand this system has one of our higher percentages of active participating users compared with some of our other clients.