I feel like there's something to this line of inquiry or something like it, and obviously I'm leaning towards 'consciousness' not being obviously useful on the whole. But consider:

'Consciousness' is a useful concept if and only if it partitions thingspace in a relevant way. But then if System A is conscious and System B is not, then there must be some relevant difference and we probably make differing predictions. For otherwise they would not have this relevant partition between them; if they were indistinguishable on all relevant counts, then A would be indistinguishable from B hence conscious and B indistinguishable from A hence non-conscious, which would contradict our supposition that 'consciousness' is a useful concept.

Similarly, if we assume that 'consciousness' is an empty concept, then saying A is conscious and B is not does not give us any more information than just knowing that I have two (possibly identical, depending on whether we still believe something cannot be both conscious and non-conscious) systems.

So it seems that beliefs about whether 'consciousness' is meaningful are preserved under consideration of this line of inquiry, so that it is circular/begs the question in the sense that after considering it, one is a 'consciousness'-skeptic, so to speak, if and only if one was already a consciousness skeptic. But I'm slightly confused because this line of inquiry feels relevant. Hrm...