As someone who makes heavy use of redux-rx[1], this looks fantastic. While using Redux, one of the greatest productivity gains I encountered was moving more parts of my application to frp. In particular, I've found that reflecting portions of my apps state in the URL was challenging with vanilla redux + redux-router, as I had many actions that relied upon componentWillMount and componentWillUpdate watching the url for changes.
Fastflux looks like a step in the right direction towards the promised land of of a functional-oriented UI written with javascript.