Robin Hanson dredges up fears I keep trying to bury:

There are (at least) two ways to implement a (Star Trek style) transporter:

  1. A space-time wormhole takes you “directly” from here to there, or
  2. We scan you, send the info, make a new copy at the other end, and destroy the original.

A similar comparison applies to two types of super-watches.  Super watches have one button.  When you are wearing a super-watch, and push it’s button, you turn it on.  Soon after, a person appears next you who looks and thinks just like you and who shares all your memories.  This person is free to walk away.  The second time you push the super-watch button, it turns off.  And you dissapear.  The second button push is also triggered automatically a given duration after the first push, or if you are about to be harmed by something.  Super-watches with longer durations cost more.

Horrifying.