Disclaimer: Nix(OS) developer, I am biased.

It's very important for us to get such feedback. This allows us to improve and move forward.

In Nix defense I think it's not worth comparing stability yet, although that is the most important aspect for users.

What matters currently is how many smart people grasp the idea why we're fundamentally better by architecturing the language and packaging problem itself and any help we get to move us forward.

For fair comparison you should note that we have ~800 contributors, probably more than 90% are on Linux. Meanwhile Homebrew packages have almost 6000 contributors.

We have recently added 4 macs to our build farm at http://hydra.nixos.org/machines, but we desperately need more developers that care. Not 6000, just a few more.