I've been using Kakoune for about a year, after a year of vim, after several years of Sublime. It has its warts, but it's way above and beyond anything I've used before. Whenever I use another editor I feel freakishly slow now. The big non-editing related thing it did for me was to make me appreciate the unix way — it really does one thing really well, leaving window management to tmux, and plugins to shell scripting, while maintaining its own client-server architecture to decouple various components. I'm not a huge fan of tmux or bash for scripting, but the open-endedness of kakoune's architecture on top of the great editing model really makes it a safe choice to invest in.