Sadly, math requires me to pick some sort of number. I was mostly just tired of hearing "cryonics wins because it produces infinite years, vs finite mortal years." It takes a very optimistic assumption to produce an infinitely long and still-fun immortal life, and seems to be less reasoning and more a Pascal's Wager.
I figured Fun Theory would produce a quick and relatively unobjectionable number, and certainly didn't think I could produce a better number via any other method. The actual value is relatively unimportant to me, and I recognize the sequence as being especially tentative.
If one wishes to conclude that there is no viable number due to the error bars being too huge, that's fine. It just means "years lived" is an unevaluable criteria.
I've run in to the argument that cryonics beats VillageReach on a simple "shut up and multiply" level, by assuming an infinity vs finite tradeoff. Having read the Fun Theory sequences, it struck me that this wasn't a reasonable assumption, so I sat down, re-read a few relevant posts, shut up, and multiplied.
In Continuous Improvement, Eliezer ballparks a good fun-theory life as having a maximum length of around 28,000 years. In Robin Hanson's Cryonics Probability Breakdown, he assigns cryonics a conjoint probability of about 6%. 28,000 * 0.06 gives us a net return of 1,680 expected years.
Full body suspension from the Cryonics Institute currently costs $28,000.
VillageReach, according to GiveWell, can save an infant's life for less than $1,000.
For the price of Cryonics, we thus save 28 lives. 1680 expected years, divided by 28, puts the break-even point at an average lifespan of 60 years for those infants saved. A quick peak at Wikipedia suggests that the average African life is under 60 years for the majority of the continent, although there are some important nuances to really get a full picture.
Obviously, these are rough numbers, and I doubt many people base their decisions solely on "years lived". I do find it rather interesting that cryonics is currently about on par with one of the most effective charities in the world on that metric, however :)