It's useful to distinguish between types of skepticism, something lsparrish has discussed: http://lesswrong.com/lw/cbe/two_kinds_of_cryonics/.
kalla724 assigns a probability estimate of p = 10^-22 to any kind of cryonics preserving personal identity. On the other hand, Darwin, Seung, and Hayworth are skeptical of current protocols, for good reasons. But they are also trying to test and improve the protocols (reducing ischemic time) and expect that alternatives might work.
From my perspective you are overweighting credentials. The reason you need to pay attention to neuroscientists is because they might have knowledge of the substrates of personal identity.
kalla724 has a phd in molecular biophysics. Arguably, molecular biophysics is itself an information science: http://en.wikipedia.org/wiki/Molecular_biophysics. Depending upon kalla724's research, kalla724 could have knowledge relevant to the substrates of personal identity, but the credential itself means little.
In my opinion, the more important credential is knowledge of cryobiology. There are skeptics, such as Kenneth Storey, http://www4.carleton.ca/jmc/catalyst/2004/sf/km/km-cryonics.html. There are also proponents, such as http://en.wikipedia.org/wiki/Greg_Fahy. See http://www.alcor.org/Library/html/coldwar.html.
ETA:
Sebastian Seung stated plainly in his most recent book that he fully expects to die. "I feel quite confident that you, dear reader, will die, and so will I." This seems implicitly extremely skeptical of current cryonics techniques, to say the least.
Semantics are tricky because "death" is poorly defined and people use it in different ways. See the post and comments here: http://www.geripal.org/2012/05/mostly-dead-vs-completely-dead.html.
As Seung notes in his book:
Irreversibility is not a timeless concept; it depends on currently available technology. What is irreversible today might become reversible in the future. For most of human history, a person was dead when respiration and heartbeat stopped. But now such changes are sometimes reversible. It is now possible to restore breathing, restart the heartbeat, or even transplant a healthy heart to replace a defective one.
Thank you for this reply - I endorse almost all of it, with an asterisk on "the more important credential is knowledge of cryobiology", which is not obviously true to me at this time. I'm personally much more interested in specifying what exactly needs to be preserved before evaluating whether or not it is preserved. We need neuroscientists to define the metric so cryobiologists can actually measure it.
If it's worth saying, but not worth its own post, even in Discussion, it goes here.