The app store updates aren't really THAT big of a problem with Apple. I mean it isn't pleasant for sure. But you can use TestFlight or something while still in beta. I'm not sure that will scale to product/market fit but it will scale enough to give you good engagement metrics.
We've been using TestFlight to distribute new builds to multiple clients around the world, distributed to their user's iPads with a notification through mail, during their user acceptance testing phase and it just works great! None of our users complained about Test Flight's UI for sure!
