[allthetime]

Why? I use a similar model in a few mobile apps. Free, not logged in usage stores a restricted set of user activity data ephemerally (lost upon uninstall) in the phone. For subscribed users, this offline storage mechanism is still the primary storage mechanism, but then we add a cloud sync mechanism on top of it that enables usage across multiple devices and permanent storage in the cloud. Curious why you need to write the app twice when in my mind you are simply adding and enabling extra functionality on top of the core product.

[vmg12]

One of the hard issues was supporting full text search locally and in the cloud. Also it's not that the entire app needed to be written twice but that parts of it needed it needed to be written twice.