I've never heard an SHM-CD disc, but the consensus on hi rez audio discussion boards is that SHM-CD is not a hi rez recording format and that the audio quality cannot approach SACD or DVD-A. Basically, they are they are the same recording as the original CD they were derived from, just imprinted on a different material. Not remastered, and certainly not worth the kind of prices they are charging. A marketing scam.
Here's a quote --
"FWIW, I’ve done a number of comparisons between SHM-CDs and their regular redbook counterparts. My conclusion is that it’s completely title-dependent. Some SHMs are quite good, while others are pure garbage. While I own several SHM-CDs (I bought them mainly out of curiosity), overall I simply can’t justify the premium that these discs command—not in sonic terms. And I have a hard time getting past the idea that it’s just another scheme to market the same titles to consumers for the umpteenth time."
In the past year, having upgraded my audio player to a high quality SACD player, I now can hear significant audio improvement of SACD over standard redbook CD. I now typically buy SACD version of recordings when available. So, it's not just a money thing for me. SHM-CD is just not worth extra dollars to me.