Do you have a blog post about it or something? I don't have specific questions, I'd just love to see how Nix looks in production.
It's still Linux but a lot of common problems go away. E.g. if you remove a user from your config then it's removed on the server (as opposed to Ansible).
Or: Because you have a dependency DAG all services that need restarting after a change are known (no more Chef notifies :restart).
Or: No more apt-get dist-upgrade. You can have a single package depend on an entirely new version of your OS and keep the old OS in place (except for the kernel version of course).