This is getting pretty circular here :lol:
I think the major problem is that "I" stop to exist. Purely objectively, in case of a teleporter, I am destroyed and a perfect copy of me will be created at the destination. Since the copy is perfect, it will be me to itself and all the rest of the world, and it will proudly proclaim that the teleport works, since it also has the memory of entering the teleporter and getting out at the other side. Objectively, there's absolutely no difference.
The problem here that concerns T.Neo (and me for that matter) is not so much one of metaphysics, but of subjectivism. I am NOT the copy, although the copy is I. This would become clear if I wouldn't get destroyed on the sending platform. The copy emerging at the other end has full right to proclaim that it is I, since it stepped on the teleporter and stepped through it, coming out at the other end. Yet "I" am still around and cannot claim to be the copy, because all I did was stay on the platform. Hence I would say that the Teleport didn't work, while my clone would say that it worked. This shows that I and the clone are not the same.
In short, if "I" get destroyed in the sending process, "I" will seize to exist. I won't even notice it of course, but subjectively, I am no more. Although the clone has full right and reason to think it is "I", "I" cannot be him. That's what it comes down to on the subjective level.