Don't underestimate the stickiness to small teams. We did switch to Slack from HipChat (which was fine) and we love Slack. I imagine a deal of disappointment among the 6 people in our company if we switched to something else - especially something almost Slack.

Slack is one of the first companies walking around with a billion dollar valuation that makes me go... "Yeah, maybe..." We use it. We love it. It's mature, well designed, gets improved constantly, and is used by more local businesses I know than not. It provides real, actual benefit to our small organization above and beyond what we pay for it.

Slack, to me, is a real product, with a real revenue stream and real value to teams. I really hope they never get bought and acquired or rolled in to a larger organization. The app is a constant joy to use - I can only say that about one other program I use daily.