I'm well underway on a large React app using Reflux for my flux implementation and I'm loving it. It removes just enough boilerplate and adds just enough sugar to keep your flux app sane. The string based event comparison in Flux's dispatcher just didn't feel right to me. Reflux actions act as their own dispatchers and works out great.
Was just reading about McFly https://github.com/kenwheeler/mcfly yesterday morning. There's another library like this too, I think. Hopefully the authors can all come together behind one of these things.