(3) To solve your first problem, remember that a definition is independent of its rhetorical purpose: that is, it tells you what we're talking about, but it does not force or "backdoor" any sort of metaphysics upon you. To solve your second problem, realize that you're committing a fallacy of equivocation: you're assuming that because something is ontologically subjective -- that is, it only makes sense in the context of a subject which experiences it -- that it is epistemically subjective -- that is, it can only be known, talked about, and reasoned about, by that subject who experiences it.

(4) Just look at the words you chose: "I perceive a very disjointed self." You chose the singular 'I' and the singular 'a self'. As a subject, you would like to be just one subject -- you would like all of the parallel efforts of your different neurons to identify one "me". But then suddenly you're astonished that all of your experiences must be described as unifying into a single whole, which can't simply be treated as separate senses, but come to you as part of one whole conscious experience. That in turn astonishes me.

If you believe Sperry's ideas on his split-brain patients, then yes, there is evidence that to divide the brain creates two conscious processes, simply by cutting off communication between parts of the brain. I guess you could add that to the list above, although it's not unique to quantum processes -- but if consciousness were caused by something quantum, then you would indeed expect that two systems which could no longer entangle could no longer form the same consciousness. But this is also true for certain classical systems, like computer networks, and might just as easily be described as a network effect -- which is why I didn't include it.

Re your discussion that cars are a bad example: I agree; I used them because (1) they were your example and (2) I never proposed that we "need to bring in quantum mechanics to explain why we don't understand the brain." Again, the question I was answering was, "why are some researchers so quick to blame our failure to understand consciousness on quantum mechanics when we don't yet understand the classical parts of the brain?" -- which presumes an agreement that yes, the brain is indeed something whose classical parts we don't yet understand. The question was "why might some people reasonably think that quantum mechanics will form an essential part of the theory?"

(5) It doesn't matter what people agree or disagree. What is pivotal about the Star Trek transporter case, what I am trying to articulate, is that it creates all sorts of difficult problems about identity. In particular, quantum consciousness theories, while often functionalist and materialist, see an opposition from much of what passes presently for materialist functionalism. This particular brand of materialist functionalism has certain philosophical problems, because they conceptualize consciousness as some sort of logical pattern or arrangement. So, for example, if a computer simulated a brain, even though we would say that there is no "brain" per se, presumably these people would say that there is nonetheless consciousness.

Now, the problems are diverse, and since I mentioned above the ontological/epistemic subjectivity distinction of Searle, I would like to raise that in the same articles Searle also mentions an observer-relative vs. observer-independent distinction: whether something is a computation depends on how you look at it, he points out -- but whether you are conscious should not depend on how I look at you.

That's not the Star Trek problem. The Star Trek problem comes instead, for me, from a book called Reasons and Persons by Derek Parfit -- it's relegated to part three of the book, but otherwise it's a good read, and you can skip to the chapter if you want without missing anything. There are an abundance of things which you might think "make you you," or more generally, make you the same person as you were five minutes ago, or even five years ago. But thinking about the Star Trek transporter, and one's visceral reactions to certain stories about imperfect transporters, tends to make many of these philosophically problematic. The problem is that even though there are two people who are qualitatively identical in the world, they are not "the same person" in the above sense. So the fact that you are "the same person" as someone five minutes ago would appear to not depend on any particular quality or aggregate of qualities. Qualities wouldn't make you who you are.

You've added, as I see it, that since the universe is quantum, even physical continuity can be made epistemically ill-defined if the replicas are sufficiently exact, but I don't think materialists would have a real problem with that.

But here's where a quantum approach could have a benefit: in a quantum theory of consciousness, qualities perhaps could make you who you are. The whole thought experiment crumbles if the device is not even in principle realizable, and that's precisely what quantum mechanics purports to offer.

(5b) The "it" is quantum mechanics.

(5c) First off that's not what I claimed -- I claimed that "some of the building-blocks of warm-and-fuzzy consciousness just fall out." Second, you're in luck: if Newtonian mechanics is sufficient to you, then Ehrenfest's theorem makes consciousness fall out of quantum mechanics, problem solved. Unfortunately, your "theory" requires modification because the "thermal noise" is quantum and the "deterministic parts" are not deterministic at bottom, but other than that, I invite you to use whatever your theory is, and apply your Hamiltonian with the Schrodinger equation rather than with Hamilton's equations of motion. On average, you'll get consciousness out again. QM does not take away; it adds.