Larry, I'd only read some passing mention of SHM-CDs, but I took some time now to read a bit more. The bottom line from what was read is that it appears to be complete BS. The claim is that it has a new polycarbonate that features "...improved transparency...allowing for more accurate reading of CD data...". Of course, all digital audio and video discs are of polycarbonate construction, using polymers formed from monomers linked with carbonate groups. One of the characteristics of the polycarbonates which makes them suitable for this purpose is their very high transparency, comparable to glass, and I've never before read even a suggestion that even higher transparency would be useful. The laser beam just has to be able to see the point where the disc changes from one level to another, e.g., from a land to a pit or vice-versa(which is read as a digital 1), elsewhere the level part is read as a digital 0. There's no transparency problem and no subtle variations of 1 and 0 that would be subject to a "more accurate reading".
Of course, as Mark mentions, many CDs might possibly benefit from remixing/remastering and exhibit improved sound, but this is an entirely different matter from claiming a fictitious benefit from modifying the polymer.
