I'd like inheritance / polymorphism. For example, would love to subclass `AppUser` from `User`. I realize it's on your backlog, but just figure I'd give it another +1.

To answer your question, Realm blows away Core Data & straight up SQLite. The context management (or lack thereof) is wonderful. Going further, I have found the errors self-explanatory and easy to fix. Finally, nice job throwing an exception trying to start a write block in a write block -- this forces client programmer to really think about where their writes happen instead of blindly writing all the time (and inevitably running into a nested write).