My reasoning is that if I can convince someone that even unrealistic immortality is desirable, the rest falls into place. Realistic immortality is also sort of more boring to argue about. Sorry, please don't hate me.
I disagree. Personally, I would say no to the unrealistic version, wherein I have no escape clause, every time. I simply value the negative what ifs too strongly negative for it to be a rational wager. However, rationally speaking, the only way you can say no to the realistic version is if you're Catholic or otherwise have a strong (in your own mind) reason to be unwilling to commit suicide. Or if you have some reason you want to be old and decrepit, I guess.