Interestingly, I had recently joined a team that was using Ember, and we found that Ember hampered our productivity. We switched to React and was able to rebuild 4 months of Ember work in about 3 weeks of work in React (not sure how many developers were working on the Ember app originally, but it was mainly 2 of us who built the React app), including requisite tests.
I’m of the opinion that Angular is much better than Ember (note: I have 4.5 years of experience in the Angular ecosystem, including in open source), and I think I am overall perhaps more productive with React than Angular, although I feel like there are less issues with state management in Angular, which has been a pita in React. All the libraries/frameworks have various tradeoffs ultimately, so I don’t believe there is a cure all for everyone’s preferences.
A note about JSX - I am not a big fan of it, but I see it more as having tradeoffs like more traditional templating languages, but different ones. I have been a bit resigned that this is the direction the ecosystem has turned towards, so I have personally decided to hold that dislike more loosely and focus on more important architecture issues. It does little good to let dislike over style paper over higher level issues if you can help it IMO. I don’t think we’ll ever see a perfect template language.
A rewrite is always going to take less time to build than the original poorly-specified version when people were trying to figure out what to do.
And the original team could have been more junior, or if similarly-experienced than your 2-person team, adding more people to the team without good leadership can also affect productivity---or as they say in Scrum, "velocity".
Regarding state management, have you tried MobX? It makes state management almost ridiculously simple. I've noticed a slight performance hit using it for deriving values for 60fps animations on React Natuve but in normal usage you'd never notice.
I’m of the opinion that Angular is much better than Ember (note: I have 4.5 years of experience in the Angular ecosystem, including in open source), and I think I am overall perhaps more productive with React than Angular, although I feel like there are less issues with state management in Angular, which has been a pita in React. All the libraries/frameworks have various tradeoffs ultimately, so I don’t believe there is a cure all for everyone’s preferences.
A note about JSX - I am not a big fan of it, but I see it more as having tradeoffs like more traditional templating languages, but different ones. I have been a bit resigned that this is the direction the ecosystem has turned towards, so I have personally decided to hold that dislike more loosely and focus on more important architecture issues. It does little good to let dislike over style paper over higher level issues if you can help it IMO. I don’t think we’ll ever see a perfect template language.