I had the same experience. Long time kubuntu user and various other distros. Got on the nixos bandwagon used it on a couple computers. The breaking part for me was all well supported applications was great, but where it broke down hard were the fringe or unsupported applications I was spending a lot of time building the nix configs. After a while I just couldn’t spend that much time making my computer work. Back to kubuntu lts, its so low maintenance.