I've been working on a project where we generate and synchronize view models (instead of full views like this proposal) between the server and web/app clients. We maintain (view)state in an Actor based backend, pushing updates to the clients through websockets. The client only needs to databind and render the model. This gives a really nice realtime user experience and is quite efficient.

Like SyncNinja, our architecture moves a layer of clientside code into the server. This enables more code sharing, at the cost of tight coupling between client and server (which does not matter for web but is problematic for our app clients). For use cases that need to work offline it falls apart; for that you need api's that work at the business layer and duplicate the view logic in each client.

I think SyncNinja will share difficulties we found around offline/localStorage, besides high resource usage, support for non-web clients, and all the problems you'd expect from browser differences (i.e. input prefill).