Would you step through the transporter? If you answered no, would it be moral to force you through the transporter? What if I didn't know your wishes, but had to extrapolate? Under what conditions would it be okay?

I don't see how any of that depends on the question of which computations (copies of me) get labeled with "personal identity" and which don't.

Also, take the more vile forms of Pascal's mugging and acausal trades. If something threatens torture to a simulation of you, should you be concerned about actually experiencing the torture, thereby subverting your rationalist impulse to shut up and multiply utility?

Depending on specifics, yes. But I don't see how this depends on the labeling question. This just boils down to "what do I expect to experience in the future?" which I don't see as being related to "personal identity".