So far, I've only made some (large-ish, granted) prototypes with Cljs and Om, but I've run into this as well. I ended up opting out of local state. I put view state and model state in the same atom, but I tried my best to keep them separate within the atom.

Easy replay/undo was one reason. Another reason was that I wanted to be able to take a _complete_ snapshot of the app state, for debugging purposes. A third was that I wanted to keep all the state that a component needs to know in order to render itself in one place, not many places.