Is this like forcing the escape analysis of the compiler to be perfect, by making it explicit in the programming language?

I'm wondering what kind of architectural corners this forces the programmer into ... have you found any so far?

Yes, the compiler guarantees references to data structures can't escape. I believe it does that "perfectly" :)

It certainly requires the programmer to rethink how they structure their data, as you have to think of where it is going to be stored, and how to store it in a way such that it will have similar lifetimes to what it is stored with, to get the most out of the language.