Performance was my main concern with MST, most notably if your data modelling involves A LOT of entities, things can get slow: https://github.com/mobxjs/mobx-state-tree/issues/440. Binding methods on every instance of an object is a lot of overhead.

I really liked using MST when I spent a few days fiddling with it. However, I really don't want to get trapped with perf bottlenecks I can't easily fix. Whether I'd actually run into trouble - I have no idea, but vanilla MobX is excellent enough that I'm happy sticking with it. I'd love to use MST more though.

I investigated MST for a React Native project and found the the additional overhead it created for frequent state updates was too much - in a synthetic test updating state every frame, it resulted in a 30-40% increase in CPU usage on a real device vs. plain MobX which for our application probably isn’t acceptable. If you know you won’t be making really frequent state updates or CPU constraints are less important it seems like a great option!