We definitely need some better tools. Slicing with a diamondoid chainsaw might be better than a laser. If you had a single strand of carbon nanotube, that's, what ten nanometers across? Total information loss would be down to 1:100000, which would be pretty good by comparison. On the other hand, if you had a technique that merely snapped the dendrites around a certain area, you could perhaps get the loss down to zero.
The slicing would definitely cut back on the cracking and freezing, if everything was done right. It would also be relatively easy to verify afterwards how good of a job was done in a particular case. The slices would be on slides, and it could be arranged to take them out of storage and photograph or scan them as long as their cryogenic temperature is maintained and they are held stiff.
Cracking happens due to cooling of different parts at different speeds. If you can eliminate that, you can eliminate the cracking problem. If we could distribute heat-conductive nanoparticles evenly throughout the brain prior to cooling you might not need to slice after all.
Another thought is that if you distributed nanotubes in the mix it might be sufficient to hold the material together despite the pressures that normally make it crack. This would give the heat time to escape without breaking the brain on its way out.
Cooling faster would tend to reduce brain damage from self-digestion and protect it from the toxicity of cryoprotectants. Ultimately I think the nanoparticle idea is probably something like what will lead to the first healthy mammal or person being brought back from cryosuspension, because they won't need the cracks "stitched" back together using nanomachinery.
Nanomachines are as different from nanoparticles as cars are from equivalent-sized boulders. The term "nanotech" is used for all kinds of things these days, so I try to distinguish. We use nanoparticles everyday now in everythiing from sunscreen to paint, so if you could find some that work for this cryonics stuff we might be routinely thawing and reviving people in just a few years. The brains with cracking will still have to wait quite a while longer, but I think we'll eventually be able to help them too.