I do not use the Flux pattern currently, but I am only in the beginning stages of building out this app & am inexperienced with React, and I have to coordinate getting others in this community involved too (two beginner/junior developers & a mid-level/senior developer, and 2-3 artists/designers, none with web designing experience). I have not evaluated how I want to handle state changes yet - I may just go with the Flux pattern for practicality for the beginner/junior developers' benefit career-wise.
This app is being built on io.js with Sails.js, isomorphic React, and ES6 (server and client) - I went with React because of its ability to do client-side and server-side rendering for SEO purposes. I have a working isomorphic React foundation, and working testing solution for the React code, but I still have to get a server-side testing solution up, integrating optional Steam authentication via OpenID, and figuring out build & deploy tooling into separate environments. This is on top of gathering requirements from the community & organizing it into a nice functional spec for developers to consume...it is almost like creating a startup except that it will never be for money, only for the love of the community I created ~7 years ago as a part of a larger one.
For the models with Sails, I haven't touched that yet - the plus side for me is that there is no schema yet, so I am still free to set everything up in the database as I wish. If you need to configure relations, there are details listed here: http://sailsjs.org/#!/documentation/concepts/ORM/Association... (check the types of associations listed in the sidebar on the left)
I came across the difficulty of using jspm on the server and client for an isomorphic React app I am building for an online community I run, and I was advised to just use npm (& naturally Babel). Integrating browserify with babelify into the build process was a far easier task.