Granted; we won't have definitive evidence for or against dualism until we're at the point that we can fully test the (non-) reductive nature of qualia. If people who have access to each other's private language dictionaries still report meta-feeling that the other person feels different qualia from the same mental stimulus then I'll have more evidence for dualism than I do now. True, that won't help with incomparable qualia, but it would be kind of...convenient...if the only incomparable qualia are the ones that people report feeling differently.