Slack is great, but it's adoption by popular opensource communities is problematic. Why? Because opensource communities are on the free plan, which limits search once you have 10k messages. I've had experiences where I wanted to revisit a question I had asked in a Slack channel the previous week, and been unable to find it. As a result, everyone burns out faster b/c the same questions get asked and answered over, and…
Someone in your project can manage to setup a logbot that dumps logs onto a webserver, which will be indexed by google. I suspect there are services that will do it for you, so you might not even have to setup the bot yourself. If there isn't one I'd have half a mind to build one, if it gets more projects using IRC.