From all the tribes I subscribe to, on average there's usually a new post once every hour to half an hour. Because of this low activity, I have very little incentive to comment on an article or visit Snapzu regularly. I will usually get 10 to 20-tops posts in the morning, and before I go to bed, another 20 or so.
The one thing I noticed about Snapzu is that there are very little discussion-based tribes. So far, this site functions mostly as a link aggregator. You hardly see any text posts; most posts are are just links to an external article (nothing inherently wrong with that, by the way). I would love to see communities like Reddit's /r/eatcheapandhealthy or /r/running(https://www.reddit.com/r/running). These types of communities are incredibly positive and healthy, and where 95% of the submissions are text posts and 5% links to articles or other things. This is something I personally enjoy about some of Reddit's communities. I would love to see discussions posted here more often.