Given this is a 2 channel forum, my thoughts are that object-oriented sounds don't really lend themselves to any type of purity testing.
Consider for instance a close-miked guitar that you put into an immersive audio recording. Well, now you don't have a specific L, R or even S recording of that guitar. You have a guitar recording which can be placed anywhere in the sound field, and whose exact bit shape will vary from system to system. Seems wrong for music, but probably good for live music reproduction, when trying to capture an auditorium, but seriously, those types of features have come and gone from many vendors. 2 channel stereo has never been shaken.