I work at Automattic (makers of P2) and even we don't use it as a replacement for Slack. What P2 replaces for us is all internal email. In fact, we use Slack q

I work at Automattic (makers of P2) and even we don't use it as a replacement for Slack. What P2 replaces for us is all internal email. In fact, we use Slack quite heavily ourselves, for any real-time/synchronous discussions. P2 is for non-realtime/async discussions, and more or less serves as the "paper of record" for the company.