I'm kind of surprised to see Guix described as having a high level of QA and polishing, akin to Debian and Fedora. It's not that I have experience with it being otherwise, but I thought that I couldn't expect it to be any more polished than NixOS, given that, at least as I understand it, it's basically a remake but using scheme in place of the nix language and running in an (almost) pure GNU OS instead of linux and friends like systemd. It's younger, uses less tested technology (linux-libre/Hurd and shepherd; with the exception of scheme (not that I dislike the nix lang)), and I imagine has less of a following to test it on this niche that NixOS and Guix belong to.

I'm going to install GuixSD one of these days to try it out. Installing directly from third-party repos is something I don't remember seeing in NixOS when I tried it a year ago. I'm interested to see what other differences in design choices have been made.