This sounds eerily similar to persistent data structures (eg in FP contexts like Clojure): updated values share as much[1] as possible with their inputs, and create new values only[1] when they differ. Granted in FP contexts, this is primarily an optimization, transparent[2] to the programmer actually using those values in a program.

From the perspective of such a programmer, I can’t think of a scenario where I’d want both value and reference equality semantics for the same objects. Is it reasonable to assume that the “smartness” here is likewise focused on making immutability perform well, rather than on use cases where value and reference equality are simultaneous considerations?

1: Handwaves away implementation details. General cautions about abstractions leaking apply.

2: Exceptions may apply[1].