It's funny, I just read this and didn't remember it from when it was new. But I see that I answered 17 months ago! Now I'm going to answer the opposite -- I'm contrarian even to myself. Assuming that the same real-life level of ability to terminate my own life exists, then I'll take the 1000 years. From this:
For the first option, say, when you’re two hundred years old, you feel physically like you’re twenty. Five hundred, fifty. Etc.
it sounds like I'd get three hundred years basically never getting sick anyway, so that's a win over 100 years of never getting sick. And if I want to linger on with gradually increasing infirmity, I can make that choice day by day, just like I do right now.