Can you clarify? It seems that there's two clear cases: a) Mary has the aliefs of pain and the necessary background to imagine the experience. She learns nothing by experiencing it herself ("yep, just as expected"). b) Mary has no aliefs and cannot imagine the experience. She learns something.

Then we get into odd situations where she has the aliefs but not the imagination, or vice versa. Then she does learn something - maybe? - but this is an odd situation for a human to be in.

My impression here is that as we investigate the problem further, the issue will dissolve. We'll confront issues like "can a sufficiently imaginative human use objective observations to replicate within themselves the subjective state that comes from experiencing something?" and end up with a better understanding of Mary's room, new qualia, what role aliefs play in knowledge, etc... - but the case against physicalism will be gone.

If I ever have the time, I'll try and work through that thoroughly.