[phamilton]

I'll list some things I do in slack that I don't in IRC. Many of these are probably possible in IRC, but the fact that I don't do this in IRC suggests that there is more friction than slack.

1. Send messages to people that are offline. 2. Easily see unread messages in a channel. 3. Markdown formatting. 4. @everyone/@channel notifications (not to be abused). 5. Simple Github integration (and other apps). 6. Mobile notifications (in fact, just the overall state of "mobile")

I'm sure every single one of these could be added to irc via bot or something like that. The beauty of slack is that I can set up a slack team and do all of the above without having to really muck around with that. Much lower operational overhead.