^Nice post, as I too wouldn't teleport if I had the option not to (though near the end I got a "first steps in the Borg's existence" vibe). The question he poses "Are you the information that constitutes your consciousness or the physical substrate?" reminds me of the "conservation of information" theory. Where is the line drawn defining death; when you die, or when your brain doesn't function the same?
And here we get to one of the biggest questions in the philosophy of artificial intelligence: if something behaves in a way that is indistinguishable from consciousness, is it then conscious?
As for the demarkation line for death, that is another controversy altogether.
That question can never be answered. Nobody returns from the dead, and even if someone did, how do you prove that it's the same consciousness?
Same goes for beaming. Someone gets beamed from A to B. How do you determine if his consciousness died and a new one was created?
I don't think anyone is saying that it can be answered with complete certainty. Nor is anyone arguing with complete certainty that there is no afterlife. The evidence points towards there being none, but the question can be framed as a non-falsifiable claim, and therefore beyond the realm of science. This doesn't make the existence of an afterlife any more likely, though. It's like Carl Sagan's invisible, silent, heatless dragon in the garage: you can propose the existence of a thing that cannot ever be proved, but that's not a very good reason to believe in that thing.