[Cont., original post was cut]

As for the Cryonics Institute, well, I think this says it all:

My dear friend and mentor Curtis Henderson was little more than straight frozen because CI President Ben Best had this idea that adding polyethylene glycol to the CPA solution would inhibit edema.(Source).

As for MNT:

There is nothing magical about the prospects of nanotechnology. There are no assumptions that we will discover free energy, cold fusion, or need anything that we know violates the laws of physics. If you're not going to point out exactly what is magical about widely held beliefs about the prospects of future technology then it's safe to assume this is yet another opinion pulled out of your ass.

By now mechanosynthesis has pretty much been proven, at least in the environment of computer simulations. The things that are extrapolated from it are not so certain: For example, the Planetary Gear and other nanomechanical wonders have only been simulated using molecular dynamics, but the only way to validate that they work (That is, that the atoms won't clump together or bonds will be formed across gears) is with an ab-initio calculation, and to the extent of my knowledge this has not been done. The prospect of nanomedicine as described by Freitas is even more dubious, since it builds on the assumption that those machines are feasible. The scaling laws used by Drexler in Nanosystems (And subsequently by Freitas in Nanomedicine) are also flawed, as Richard Jones pointed out to Michael Anissimov:

With respect to the calculations in MNT, you should know that the numerical estimates of the rubbing friction of hydrogen terminated diamond surfaces you get from the formulae in Nanosystems are several orders of magnitude lower than the values obtained by Judith Harrison’s molecular dynamics simulations. This isn’t a “numerical error”, of course, it’s a result of an incomplete formulation of the relevant physics.

So while the basic capabilities are beyond doubt (In the theory), the capabilities that are presumed to arise from them are not.