This post inspired me to quickly do this calculation. I did not know what the answer would be when I started. It could convince you in either direction really, depending on your level of self/altruism balance and probability estimate.

Cost of neuro-suspension cryonics > $20,000

Cost of saving a single life via effective altruism, with high certainty < $5,000

Let's say you value a good outcome with a mostly-immortal life at X stranger's regular-span lives.

Let "C" represent the threshold of certainty that signing up for cryonics causes that good outcome.

C*X / $20,000 > 1 / $5,000

C > 4/x

Conclusion: with estimates biased towards the cryonics side of the equation... in order to sign up your minimum certainty that it will work as expected must be four divided by the number of strangers you would sacrifice your immortality for.

If you value immortality at the cost of 4 strangers, you should sign up for cryonics instead of E.A. only if you are 100% certain it will work.

If you value immortallity at the cost of 400 strangers, you should sign of for cryonics instead of E.A. only if you are more than 1% certain it will work.

(^ Really what is happening here is that at the cost of 4 strangers you are taking a gamble on a 1% chance..but it amounts to the same thing if you shut up and multiply)

The numbers for whole-body suspension will be rather different.