A bit off topic but I have been working on a native Mac slack app on and off for the past couple of years. Truly native, no web views except for the Slack oauth login.
Would ppl be interested in beta-testing it? Would ppl here be interested in paying for something like that?
Here are some links to screenshots so you know its not just vaporware :)
Seems cool. If it can use 1/10th of the memory/CPU footprint of the current Slack Atom based client (as your screenshots seem to indicate), then all the better.
Good luck with your project!