Lies travel halfway around the world while the truth is putting on its shoes. This reply is mostly directed to David Gerard, whose comments have been generally sensible except for some misinformation.

Re:

"And Alcor (Mike Darwin in particular) is famously litigation-happy against those it perceives as critics, which is a BIG cultural warning sign these days."

That Alcor has a history of suing critics is apparently becoming a self-perpetuating myth. The truth is that Alcor has a long history of litigating rights to cryopreserve its members and keep them in cryopreservation. However, since 1972, I'm not aware of anyone being sued for defamation by Alcor prior to Larry Johnson in 2009. Not that there's been any shortage of people saying false things about Alcor during all that time. Anyone who wants to know why Johnson achieved the dubious distinction of being the first to actually be sued can read the civil complaint

http://www.alcor.org/Library/pdfs/NewYorkComplaintAmendedJan2010.pdf

and other information about the case

http://www.alcor.org/press/response.html

While he may have been the first, I can't promise he'll be the last. There comes a point where defamation becomes so extreme, persistent and damaging that if you don't seek legal redress, people will assume you can't. In Johnson's case there were also other issues that no decent organization could allow uncontested, such as selling alleged photographs of the remains of Ted Williams on the Internet. Not suing for something like that would expose the organization itself to liability.

By the way, I'm not aware of Mike Darwin suing any critics, at least not in the context of cryonics. Also, Darwin hasn't done anything for Alcor since 2002, or been an Alcor employee since 1991.

Another misapprehension is that Alcor doesn't use medical professionals, or is averse to using them. This is dealt with at some length here

http://www.imminst.org/forum/topic/44772-is-cryonics-quackery/page__p__437779#entry437779

and here

http://www.alcor.org/Library/html/professionals.html

Alcor also has medical doctors among its advisors and board of directors.

The person making criticisms against SA hasn't worked there in years, and never under present management. SA in fact contracts with professional perfusionists and surgeons, despite the efforts of critics to sabotage that relationship. Something is really wrong when an organization that makes conscientious efforts to professionalize is held by critics at a lower stature than other organizations that are committed on principle to using only morticians to do cryonics procedures, and that criticized Alcor for decades for aspiring to a medical model.

Re:

"Cryonics deeply needs strong advocates who apply scepticism to it."

I don't know you if you mean skepticism in the card-carrying sense, or some other unspecified standard that you assume no advocates adhere to. If the former, for whatever it is worth, Alcor's Chief Medical Advisor, Steven B. Harris, MD, has sat on the Editorial Board of Skeptic magazine for many years and is respected for his contributions to scientific skepticism.

There are data showing the quality with which cryopreservation can preserve the fine structures of the brain.

http://www.alcor.org/Library/html/cambridge.html

http://www.alcor.org/Library/html/micrographs.html

and vitrification is currently a leading contender for the Brain Preservation Prize as a method for preserving "the connectome"

http://www.brainpreservation.org/index.php?path=prize

Finally, with respect to the question of whether there is skepticism in cryonics, and whether cryonics advocates are properly circumspect, consider this comment from a leading advocate of cryonics:

"There will never be proof that cryonics will work."

http://www.alcor.org/Library/html/NeuralArcheology.html

The basis of the comment is that there are two separate ideas called cryonics. The first is the proposition that people cryopreserved under ideal conditions with the best available methods might be recoverable in the future. That is certainly amenable to skeptical analysis and discussion, and maybe someday be provably correct. Indeed it must someday be proven correct if cryonics is ever to succeed. However the second idea called "cryonics" is that cryopreserving people even when they are badly damaged, and you don't know whether they will ever be recoverable based on present analysis, is the morally right thing to do. That idea, when adopted as a matter of principle, is hard to subject to scientific scrutiny barring obvious dissolution of the brain. However I don't think the difficulty of that scrutiny is reason to think less of people who adopt that idea as a moral principle or personal "medical" preference.