Rule of 150.. even at my current workplace, I was employee #17. Now there are 60+ people and the I can feel that the social vibe has changed drastically. Voicing my opinion has less meaning now. I believe I had the best time and productivity when we had about 20~40 people. But that's work place. In this social network type of platform, people would care less about importance of the votes. I do concur that 5-9 witness votes would increase the quality of the relationship even further.