I couldn't say. I run Nix, not Guix.

Personally the thing that holds me back from Guix is their (understandable) insistence on packaging libre/free software only. Guix looks like it has better usability than Nix, IMO, but I don't want to jump through extra hoops to get non-free software installed.

Does there not exist a community non-free repo at this point?

I don't know. If there's a decent, supported community repo -- similar in extent and quality to Nixpkgs -- then I'd consider giving Guix a proper try.