Hi Matt. We use Slack in work and love it! Four of us are based in Dublin, Ireland and four are in Belgrade, Serbia — it has really helped us build a strong company culture, it’s like we are all in the same room. However, I don’t feel more obligated to respond instantly to Slack messages than I do to emails; if someone is offline, they’re offline. I guess that means we don’t have an “always on” expectation in our company, which is nice.
Slack also hasn’t replaced email for us, it has just become another piece of the communication suite. We’re biased as we run an email startup, but believe Email still has it’s place in this suite, it’s serves a purpose for asynchronous communication, it gives time for a considered response and is a good channel of record.
I hope you don’t mind if I add an email app recommendation — https://www.hiri.com/#gethiri — Hiri is a desktop email client that that improves productivity by reducing email overload and time spent on email. Sorry to plug our product, but I think what we do is relevant to this topic, so hopefully people will find this helpful.