- There are a few video games I like whose developers have a sub-reddit as their main community hub to interact with fans, and I'm sure there are other non-gaming communities that are centered around the same idea. It's free and there are literally millions of people who use Reddit every day, so it could be worth checking out. Creating a sub-reddit is can be done within a minute or two. You have mod tools and page customization tools at your disposal, and you can even set the page to private if you wanted to.
If you are working for a company that has multiple topics at the same time running in the one department/team thinking about a feed based collaboration could be a good option.
With Workplace you can organise your team in groups and discuss projects/topics via the comments on a post. This could help your team stay on topic and don't get distracted by another random comment in your chat history.
The (news) feed based way of communicating (FB) can work well for slow moving tasks or project overviews. I feel like a company with more than 50ppl could start to make real use of this kind of work.
The FB messenger really isn't on par with any of the major business chat's out their. So don't switch to FB if you really just wanna chat with your guys. You could, however, use it to supplement your Slack usage with some company feeds. But then you should save the money and use G+ which comes free with your G Suite subscription.
The pricing however is attractive. Starting at a about a dollar a month and employee it's way below industry average.
I have one team that is very tethered to email and at first blush Workplace from FB seemed like a good way to ease them into real collaboration with a familiar interface. I would still recommend it, but would have liked the option to interface with workplace from my existing account.