More importantly, Cloact is much closer to the React model while Om diverges quite a bit because we're interested in enabling patterns that are more difficult otherwise, trivial complete UI state rewind on exceptions/errors, trivial undo, and more powerful operations on the applicate state history oriented at interactive debugging and development.
Of course these values might not interest you and you just want a simple direct mapping onto React. Then Cloact looks awesome! :)
Yes, exactly, Cloact tries to stay really close to plain React. But since it allows you to separate data from rendering, undo should be quite trivial to implement (if you keep all your application data in a single cloact/atom)...
You could still use regular atoms, though, with some extend-type magic. But then you risk messing with non-Cloact code in horrible ways...