My GuixSD configuration is no special, because, well, it's nothing special about the operating system -- it's a boring, yet vital piece of software. The free-software version of config is absent (yet easily creatable), but it doesn't mean I'm addicted to the proprietary stuff. It's a necessity -- to have a Linux kernel and firmware for my Wi-Fi chipset -- there's no open-source module for it yet. And, also, while CLHS is a proprietary piece of documentation, owned by one of Common Lisp vendors, it's still a great piece of reference and inspirational reading -- I just can't live without it.
The dev-manifest file is the extremely heavy and slow Swiss knife for almost any coding horror I might dig into. I don't notice it's size because of the cool Guix caching. The only problem is to initially download all the necessary packages after the system reconfiguration.