you can use reagent reactions for whatever you want, not only rerendering, but to me the selling points of reagent is that it is "the beaten path" and that its main mechanisms feels obvious and straightforward. for me those benefits stop applying once you start using reactions. I imagine relatively few people use them directly, and they're subtle to use right and reason about
yet another interesting take in this area (which actually credits Javelin as an inspiration) is https://github.com/domino-clj/domino