Jason Fried has a great article about group chat software:
What we’ve learned is that group chat used sparingly in a few very specific situations makes a lot of sense. What makes a lot less sense is chat as the primary, default method of communication inside an organization. A slice, yes. The whole pie, no. All sorts of eventual bad happens when a company begins thinking one-line-at-a-time most of the time.
We’ve also seen strong evidence that the method and manner in which you choose to communicate has a major influence on how people feel at work. Frazzled, exhausted, and anxious? Or calm, cool, and collected? These aren’t just states of mind, they are conditions caused by the kinds of tools we use, and the kinds of behaviors those tools encourage.
Based on these discoveries, I’ve put together a list of the positive and negative impacts of group chat on an organization. If you’ve gone chat-first, or you’re considering heading down that path, I encourage you to review and consider these impacts on your own organization.
An absolute must-read if your company is considering using Slack, HipChat or Skype for business. We've been using Skype internally for as far as I can remember at XWiki. I couldn't see us running a distributed company without it, but the associated cognitive costs are real and should not be underestimated.