We had this in flowdock before we switched to slack, on a team of probably 700 or so at the time. It made it far easier to filter out chatter when dealing with an urgent issue (no need to change rooms or remind people to be quiet for a while), and I haven't really noticed it encouraging pointless chatter. I seriously miss this feature in slack.

What was wrong with flowdock?

I'm not sure. I think with the benefit of hindsight, I liked it better on balance, but I wasn't involved in the decision. It was definitely a terrible resource hog, even more so than Slack, and the iOS client wasn't quite as polished IIRC.

that doesn't occur without threaded messaging? threaded messaging makes it easier to ignore those sub-discussions...

>that doesn't occur without threaded messaging?

The difference I mentioned wasn't one of occurring or not, but one of degree of occurrence.

>hreaded messaging makes it easier to ignore those sub-discussions...

Not as much as it makes it easier to start and digress into endless sub-discussions.