I identify with my upload on an intellectual level. On the emotional level, I can't really say. Whether I push the button depends on whether I judge "1000 years of agony, then immortality with no memory of the pain" to be better or worse than dying tomorrow, and then on whether I had the guts in the moment to push the button. I want to say I'd go for it, but I don't think I know myself that well.
Oh, by the way: is it one branch of me dying tomorrow and the other being painfully uploaded, or is there only one me with a choice between the two? I interpreted the question as the latter. If it's the former, the doomed branch would probably find the knowledge that another branch of me was being uploaded at least somewhat comforting as the [cataclysmic event] was taking place, and I feel like I'd be more likely to push the button.
I have been trying to absorb the Lesswrong near-consensus on cryonics/quantum mechanics/uploading, and I confess to being unpersuaded by it. I'm not hostile to cryonics; just indifferent, and having a bit of trouble articulating why the insights on identity that I have been picking up from the quantum mechanics sequence aren't compelling to me. I offer the following thought experiment in hopes that others may be able to present the argument more effectively if they understand the objection here.
Suppose that Omega appears before you and says, “All life on Earth is going to be destroyed tomorrow by [insert cataclysmic event of your choice here]. I offer you the chance to push this button, which will upload your consciousness to a safe place out of reach of the cataclysmic event, preserving all of your memories, etc. up to the moment you pushed the button and optimizing you such that you will be effectively immortal. However, the uploading process is painful, and because it interferes with your normal perception of time, your original mind/body will subjectively experience the time after you pushed the button but before the process is complete as a thousand years of the most intense agony. Additionally, I can tell you that a sufficient number of other people will choose to push the button that your uploaded existence will not be lonely.”
Do you push the button?
My understanding of the Lesswrong consensus on this issue is that my uploaded consciousness is me, not just a copy of me. I'm hoping the above hypothetical illustrates why I'm having trouble accepting that.