There were two ways to interpret your statement - that uploaded won't be identical human beings (an empirical statement) vs. uploads will disrupt your continuity (a philosophical statement).
The latter, but they are both empirical questions. The former deals with comparing informational configurations at two points in time, whereas the latter is concerned with the history of how we went from state A to state B (both having real-world implications).
How do you know right now that you are a continuity of the being that existed one-hour-in-the-past, and that the being that exists one-hour-in-the-future will be in continuity with you?
We need more research on the physical basis for consciousness to understand this better such that we can properly answer the question. Right now all we have is the fleeting experience of continued identity moment to moment, and the induction principle which is invalid to apply over singular events like destructive uploading.
My guess as to the underlying nature of the problem is that consciousness exists in any complex interaction of particles - not the pattern itself, but the instantiation of the computation. And so long as this interaction is continuous and ongoing we have a physical basis for the continuation of subjective experience.
Would you ever step into a sci-fi style teleporter?
Never, for the same reasons.
Cryonics constitutes "pausing" and "resuming" yourself. How is this sort of temporal discontinuity different from the spatial discontinuity involved in teleporting?
Pausing is a metaphor. You can't freeze time and chemistry never stops entirely. The particles in a cryonic patient's brain keep interacting in complex, albeit much slowed down ways. Recall that the point of pumping the brain full of anti-freeze is that it remains intact and structurally unmolested even at liquid nitrogen temperatures. It is likely that some portion of biological activity is ongoing in cryostatasis albeit at a glacial pace. This may or may not be sufficient for continuity of experience, but unlike uploading the probability is at least not zero.
BTW the problem with teleporting is not spatial or temporal. The problem is that the computational process which is the subjective experience of the person being teleported is interrupted. The machine violently disassembles them and they die, then somewhere else a clone/copy is created. If you have trouble seeing that, imagine that the process is not destructive. You step into the teleporter, it scans you, and then you step out. I then shoot you in the head with a gun. The teleporter then reconstructs a copy of you. Do you really think that you, the person I just shot in the head and now is splattered all over the floor, gets to experience walking out of the teleporter as a copy? If you're still having trouble, imagine that the teleporter got stuck in a loop and kept outputting copies. Which one is you? Which one do you expect to "wake up" as at the other end of the process?
The problem is that the computational process which is the subjective experience of the person being teleported is interrupted.
It sounds to me like you're ascribing some critical, necessary aspect of consciousness to the 'computation' that occurs between states, as opposed to the presence of the states themselves.
It strikes me as similar to the 'sampling fallacy' of analog audio enthusiasts, who constantly claim that digitization of a recording is by definition lossy because a discrete stream can not contain all the data needed to reconstruct a continuous waveform.
Background:
On the most recent LessWrong readership survey, I assigned a probability of 0.30 on the cryonics question. I had previously been persuaded to sign up for cryonics by reading the sequences, but this thread and particularly this comment lowered my estimate of the chances of cryonics working considerably. Also relevant from the same thread was ciphergoth's comment:
Based on this, I think there's a substantial chance that there's information out there that would convince me that the folks who dismiss cryonics as pseudoscience are essentially correct, that the right answer to the survey question was epsilon. I've seen what seem like convincing objections to cryonics, and it seems possible that an expanded version of those arguments, with full references and replies to pro-cryonics arguments, would convince me. Or someone could just go to the trouble of showing that a large majority of cryobiologists really do think cryopreserved people are information-theoretically dead.
However, it's not clear to me how well worth my time it is to seek out such information. It seems coming up with decisive information would be hard, especially since e.g. ciphergoth has put a lot of energy into trying to figure out what the experts think about cryonics and come away without a clear answer. And part of the reason I signed up for cryonics in the first place is because it doesn't cost me much: the largest component is the life insurance for funding, only $50 / month.
So I've decided to put a bounty on being persuaded to cancel my cryonics subscription. If no one succeeds in convincing me, it costs me nothing, and if someone does succeed in convincing me the cost is less than the cost of being signed up for cryonics for a year. And yes, I'm aware that providing one-sided financial incentives like this requires me to take the fact that I've done this into account when evaluating anti-cryonics arguments, and apply extra scrutiny to them.
Note that there are several issues that ultimately go in to whether you should sign up for cryonics (the neuroscience / evaluation of current technology, estimate of the probability of a "good" future, various philosophical issues), I anticipate the greatest chance of being persuaded from scientific arguments. In particular, I find questions about personal identity and consciousness of uploads made from preserved brains confusing, but think there are very few people in the world, if any, who are likely to have much chance of getting me un-confused about those issues. The offer is blind to the exact nature of the arguments given, but I mostly foresee being persuaded by the neuroscience arguments.
And of course, I'm happy to listen to people tell me why the anti-cryonics arguments are wrong and I should stay signed up for cryonics. There's just no prize for doing so.