We tried kanban with a few teams at my last startup. It worked great for a team with a clear direction, but was really hard from a management/planning/accountability standpoint. It didn't mesh well with the quarterly planning cycle the rest of the company aligned on. So we took some of the key tools (like WIP limits) but otherwise moved to scrumban type process. It was a bummer, because we had some solid data on increased productivity, but couldn't really deliver increased predictability (not that scrum was more predictable in-practice, it just seems that way)