I don't think that would be a good test, either. All that would prove is that there exists a storage device, and a method by which to read it. It doesn't imply that the recording device is conscious.
Disagree, it would additionally show that the storage device was in a natively consciousness-readable format, and that's just for memory sharing. Experience sharing, if that's what the "light in one cage, button in another, reward for both" study really shows (as opposed to, say, short-term memory sharing that appears like experience sharing to an outside observer) would seem to directly suggest the circuitry of consciousness. Of course it can't be completely proven, but neither can anything else.
