Cryonics actually works (probably), and is cheap (definitely). SENS, on the other hand, is speculative, and needs $ hundreds of millions at the minimum to get to work.
I'd say that the marginal utility of money for the first $100M would be better spent almost entirely on marketing cryo.
After that, then maybe some exploratory work on SENS... though it would be an uphill battle against both a fiendishly hard scientific problem, AND public opinion. Cryo, on the other hand, you just have to sell it. (And that might be relatively easy, i.e. 1 million signups for $100M in promotional work)
On the other hand though, I think that if SENS actually worked, it would make a lot more of a difference to the world than if we successfully marketed cryo to a million nerdy-types.
So actually, maybe SENS is the better investment, if you have big money and you're an altruist.
With smaller money and more egoism/desire to save those who are more like you, cryo-marketing.
SENS, on the other hand, is speculative, and needs $ hundreds of millions at the minimum to get to work.
If you're talking about the cost of R&D, I don't think so. A lot of the work of SENS is just to find the important developments amid the mass of biological research happening every day in thousands of universities and companies. Certainly, once you grasp that big picture, you can spot gaps and call for them to be filled with specific new research, and that costs money. But I see SENS as mostly an exercise in providing a coherent strategic vision for rejuvenation research (and that's a vision that needs constant updating).
Katja's recent post on cryonics elicited this comment from Steven Kaas,
"If cryonics is super-far and altruism is seen as more important in far mode, why isn’t buying cryonics for others seen as especially praiseworthy? Your list of ways in which cryo is far-mode seems too much of a coincidence unless cryo was somehow optimized for distance."
...a comment which finally caused the following hypothesis to click into sharp resolution for me.
My guess is that it's cryonics advocates who are optimized for distance. Most people are basically natives of near mode, using far mode only casually and occasionally for signaling, and never reasoning about its contents. Even those who reason about its contents usually do so and then ignore their reasoning, acting on near mode motivations and against their explicit beliefs. Children, however, actually need to use far mode to guide their actions because they lack the rich tacit knowledge that makes near mode functional.
Some people get stuck in a child-like behavioral pattern, probably due to a mix of neurological bugs which prevent near-mode from gelling (aspergers and schizotype) and internalization of explicit (far mode) rules condemning near-mode (obsessive compulsive personality disorder). They become Shaw's "unreasonable men" and push for the universal endorsement of far-mode ideas. Since other adults don't care about the contents of far mode much anyway except to avoid being condemned for saying the wrong things, others go along with this, and there's a long-term drift towards explicit societal endorsement of altruistic norms with an expanded circle. This does matter, in the long run, because such norms provide convenient nuclei for the emergence of forms of mostly-arbitrary identity markers.
Unreasonable men also develop artificial ways of reasoning, methods of rationality, which work even when the minds innate tendencies towards reason aren't engaged by near mode. These methods don't necessarily suffer from the bugs that near-mode reasoning suffers from. Once the right set of methods, most importantly math, science, nation-states, cosmopolitan liberalism (actions permitted by default rather than banned by default) and capitalism, are developed, they enable scientific and technological evolution to jump over low memetic fitness regions of the memetic fitness landscape and discover higher fitness technologies on the other side rather than leveling off at the 'golden age' level of Hellenistic Greece, Tang and Song China, the Roman late republic and empire, the Abbasid and other advanced Caliphates, Minoan Crete and probably many other pre-industrial civilizations.
Unfortunately, as civilizations reach a higher level of development, more effort is available for indoctrination, and the indoctrination methods are based on the introspection and intuitions of these 'unreasonable men', and are thus ineffective on normal people, who simply snap out of their indoctrination when they become adults. As the unreasonable men become further indoctrinated, they become less able to make effective use of near-mode reasoning, which their morality condemns, but the methods that make far-mode reasoning rational don't make it an adequate substitute for near-mode when dealing with situations where subtlety, competition or energy are required. Ultimately, the civilization systematically destroys the ability of its unreasonable men to compete for the slots in the society where rationality is required to maintain the society's energy and the society looses the ability to respond coherently to threats and collpases.
Cryonics is a canary in the coal mine. At a certain stage of collapse, there has to be some idea that is transparently correct when one uses valid reasoning to analyze it but which is roundly rejected by everyone with near mode and is only accessible to people in extreme far mode. Once the far mode people are too ineffective to promote their ideas to the status of even verbal endorsement by the general population this idea will never rise to prominence.
I'd love to see your thoughts.