I don't feel like even attempting to try to hack together what Flowdock gives me on top of IRC. That would involve far too much of my time, and I'd rather have a team of very smart engineers dedicated to keeping it secure, running, and feature-rich, rather than relying on my time to do any of those things. I use an IDE, rather than trying to cobble an IDE together in Vim, for the same reason.

> I can sort of understand Slack for a small company, but if you have your own server infrastructure, no, I can't.

This seems to be based on the assumption that IRC is anywhere near as feature-rich as a web-based chat client, but it isn't. If you could point me to an OS X IRC client that isn't absolutely terrible (and please do, I'd really love one), I'd be happy to give it a shot, but even with all of the above perceived advantages of IRC, Flowdock still wins for me. Every team I've worked on that's switched to it has had a marked uptick in productivity.