Changing the issue from murder to suicide might be interesting.
You're the leftover meatsack. You wake up after the upload, and see UploadedYou frolicking in a virtual world. What would you have to see to shoot yourself in the head?
I doubt that's going to seem like a good idea to this meatsack.
My two selves share memories, one of them slowing down for the occasion, and agree to kill their less useful body. See also Jack's comment, though I don't think it influenced me.
In this video, long about 48:00, Eliezer talks about uploading and about how it wouldn't be murder if his meat body were anesthetized before the upload and killed without regaining consciousness.
It's arguable that it wouldn't be murder, but I'm not clear about why Eliezer would want to do it that way. I've got some guesses about why one might want to not let the meat body wake up (legal and practical complications of a double but diverging identity, the meat version feeling hopelessly envious), but I'm not sure whether either of them apply.
On the other hand, I can think of a couple of reasons for *not* eliminating the meat version-- one is that two Eliezers would presumably be better than one, though I don't have a strong intuition about the optimum number of Eliezers. The other, which I consider to be more salient, is that the meat version is a backup in case the upload isn't as good as hoped.
More generally, what would folks here consider to be good enough evidence that uploading was worth doing?