I see many users leaving the steemit.com front end and using the threespeak front end. While that doesn't have any affect on votes/posts on steem, it impacts the traffic/website numbers of people visiting steemit.com.

Regarding retention and engagement levels... I see that they use a main account to upvote a lot of their users which will surely help with retention. In fact, I was pushing for the main steemit,inc account to be used like that long ago in order to help bring content creators over. I would probably still be open to that if it was used solely on high profile influencers. Overall, I think threespeak is overwhelmingly positive for steem but perhaps not so positive for steemit.com as they lose ad revenue as more and more people switch over.