Considering the fact that you want to use more Voice/Screenshare channels, well just use Discord, that is a no brainer. Running your own server would be a pain, and Discord is so much better with voice channels than Slack that is hard to compare.
I think that what I got wrong was that I focused all the attention in the IRC without considering StrapiConf and live AMAs.
Is actually a great idea to have the conference in the same place than the community chat