One of these days I'll try guix (currently on NixOS).

Two things that hold me back (aside from the obvious friction of switching):

1. nixpkgs is huge. If what I need isn't in 25.05, it's in unstable

2. I've been programming in Common Lisp for so long that I can't help but write buggy code any time I try writing in a lisp-1. It seems like it should be such a minor thing, but I invariably inadvertently shadow a function I'm using with some other variable.

[edit]

I forgot my third issue, which is all of my preferred setup options seem to be further off beaten path in Guix than NixOS (e.g. plasma, zfs)