But according to the though experiment you'd set up [...]

I think you're confusing me and Yvain. I'll take that as a complement, though!

I agree with pretty much everything you've said here - but it's posed as though to stand as an argument against what I think, so I'm a little bit concerned that we're not talking about the same thing. For instance, you say:

Thus, again, I see no need for dualistic assumptions of any kind, which includes qualia.

I agree, dualism is unnecessary as far as we know. It's hard for me to conceive of a type of evidence that would ever suggest that we need dualism.

However, the existence of qualia does not immediately require dualism. The term "qualia" just points to the experiences we have that currently seem to sit on the "other side" of the hard problem of consciousness with respect to our current empirical knowledge. Presumably, we will eventually find a reductionist answer to the hard problem of consciousness. In the meantime, though, we still need a way of talking about the phenomenon in question. Qualia don't play the same role in this question that vis vitalis did with vitalism; it isn't that we're trying to answer the hard problem by saying "subjective experience is made up of qualia", but instead we're trying to describe how subjective experience presents itself to us. We see red, and this experience of redness seems to have a certain character to it, so we tag it with the descriptor of being the quale of red. The question is, how is it that there is a conscious experience induced by neurons firing in response to stimulation of the optic nerve? We know how visual perception works, but as far as I know we don't very well know how the quale of red appears from that. It's a statement of the question, not a phlogiston-class proclamation masquerading as an answer.

Does that clarify where I'm coming from on this? It's not dualism (or at least I'm pretty darn sure it's not!); it's just naming a confusion in as much detail as possible.