The benefit would be: changing stuff doesn't break it. And if it does you can easily roll back.
Keeping the config file sets up a new installation like the old one without trouble. Somehow I don't think you really need it if you aren't distro hopping but I need it way too much.
Currently the trade offs are too big I think. Programs don't work because of the atomic behaviour.
And the learning curve is steep even for Linux veterans.
My heart is always with Debian, but Bazzite is a surprisingly useable immutable OS. I would suggest using it for your core suite then use Distrobox w/ Debian for any apps outside of that. It's so snappy!
You don't need nixos for that. The only thing you lose is rolling back system configuration, unless you use system-manager.
Unless you're doing scientific computing, or being a sysadmin for a company, you don't actually need nixos. It's at that scale that system reproducibility becomes important enough to offset the downsides. For everyone else, home-manager and a list of packages are more than enough.
The learning curve is not that bad, it's just that the resources are a pile of burning garbage.
Also, idk what you're doing with VLC, but ~/.config should still work AFAIK.
I did install vlc. I started vlc. I noticed completely wrong subtitle size. I went to settings and tried to change some and save. Vlc throws an error it can't save the file, permission error.
I install vlc with flatpak. Same subtitle error. I go to the settings, I don't get an error but the settings don't change anything.
Also almost anything i do in the plasma settings doesn't get saved.
And that shit should only be saved in the home folder.
I gave up on nixos long before getting to that point. On Debian I use apt for to install a few user packages like alacritty because of Nix issues. Everything else is pretty much the same linux experience.
The documentation is rare and the atomic behaviour seems to break my whole Linux work flow.
Which is a good thing I guess. But I can't Google "how to do x on nixos" and get a reasonable answer. I get nothing. Or some weird forums where I don't know what they are talking about.