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?