Perhaps you can answer this: does Hanson start from a factually wrong claim about sufficient conditions for brain emulation? Would we need to know the strength of the connections within the brain, as this link claims, and does this pose more difficult problems?
I am not a brain scientist myself. I think that knowing strength of connection as well as plasticity are both very important. In fact, I think that plasticity considerations are one of the main things that Penrose correctly addresses in The Emperor's New MInd. However, from a graph-theoretic and machine learning point of view, this does not strike me as intractable. Just yesterday I witnessed some new results in the connectomics project in which they can essentially (95+% accuracy on training data sets) reconstruct the wiring diagram of non-trivial volumes...
Here's a great article by Paul Allen about why the singularity won't happen anytime soon. Basically a lot of the things we do are just not amenable to awesome looking exponential graphs.