At Symflower we do, one of us has it as its main editor and it looks extremely productive. As a former VIM hardcore user i enjoy the pair programming sessions. I guess these sessions must feel the same way when a non-VIM user watches a VIM hardcore user.

We even have an extension for Symflower https://github.com/symflower/symflower-kakoune that is how much we appreciate Kakoune.