Sblack is an ultralight Slack client built with Slack's core features in mind, it also comes with a Dark mode theme
Interestingly as far as i see from Activity Monitor, it uses more RAM (with the name of your Slack url) Dark mode is useful but needs small touches, otherwise i didn't find it useful (text color shouldn't be #fff for example, or file uploads shouldn't be sharp black #000) and also there are minor bugs about the dark theme..
As a conclusion; idea is good, execution needs more attention.
Pros:Dark Mode
Cons:Higher RAM usage
I love this idea and the dark mode works well for most of the interface. The dealbreaker for me is that it doesn't support calls, if you ever want to call or screenshare then you're better off with the native app.
Pros:Dark mode for slack
Cons:Doesn't support calls