I do believe Redux's single Store solves one of the biggest React problems, which is passing props along all children components – but, as you said, I miss having good guidelines to help developers reason whether it makes sense to store all state info in a Store, or rather in a local state.

I'm sure (or at least I hope) those questions you've stated will be answered throughout time, since we're dealing with a fairly new technology and architecture.

Thanks for the comment and the GitHub issue reference! :)