Why would one want to increase the complexity of the application by introducing "yet another new thing" on an already complex architecture.
I am just not sold on React. If someone could show a demo of why should we use React instead of, Backbone.View for example, then we can talk.
1) Performance -- React, with it's Virtual DOM, and the new idea to treat the DOM as an expensive remote rendering pipeline will give you a huge performance boost.
2) Compose-ability & Modularity -- While React only serves as the "view", there's huge potential for really decoupling your application.
3) Library, not framework -- The notion that React is simply a library is awesome. While I'm not a huge fan of the 1000nd super small libraries to make up your app, without any magic or complexity; I enjoy not being locked-in to a particular solution. Especially when new (potential) solutions are being presented regularly. I think modularity will win in the end. If React doesn't serve your needs in 6 months, then you can easily (still involves work, though) switch it out for something better. But, if you use something like Ember.js, you're tied into it's ecosystem and framework.
Then again, Knockout would also be pretty good at this, so I dunno. There are a lot of criteria for evaluating a framework... development speed, maintainability, simplicity, functionality. And a lot of it is better evaluated experientially rather than theoretically.