Well, yeah, it wasn't just a factor of less than two. Discounting rates, decrease of marginal u / $, P(B) probably increasing over time, and a few other things came into account.

Not to mention the sheer increase in natural mortality rates - %-of-deaths gives you a ratio by which to cut down odds of success, but deaths-per-population is what counts in calculating expected utility of signing up for cryonics at a given time. These rates climb very sharply past 40, especially for the causes of death that cryonics can actually help with.

Overall though, I must admit (after taking another look at it) that my math is/was full of potential holes to poke at. I may be going over it more carefully at some point in the near future, or I may just end up signing up for cryonics to save myself the trouble and never have to think about it this much again (barring new evidence or other events, of course).