I love CoSo's design but most of my groups aren't here, so I'm still looking for the place the majority will end up to keep in touch.
All of my BIPOC mutuals have experienced racism and white nationalist harassment within a day of joining Mastodon. There is no real way to report & block it on a viable scale for them.
I don't see Mastodon being the next big thing if POC can't feel safe there.