11.1 says, "For this to work, the id of the resource must be retained through the round-trip process to allow for the update. This can be supported by storing the id as a hidden question not shown to the user."

I think this only applies to the definition-based and StructureMap-based approaches. If that is correct, please clarify that. Otherwise, if the Observation-based approach is used for editing existing resources, then there would need to be some mechanism for recognizing the hidden question with the ID.