We use one workspace. Everyone is welcome to "listen in" to almost all channels. We have very few private channels.
Also we were hesitant to add another software and it was so worth it. We did intially end up with way too many channels but it has slowly adjusted itself. There was a tension and then people deleted and combined stuff so there wasn't so many. I will say I wish I did more training on functions, using threads, and setting notifications because there was some miscommunication and frustration intially.
Jenn