I own a number of SHM-CDs and I agree that it's a title dependent proposition. As I posted in other threads when they first came out, if the original sounds excellent then the SHM gives it just a bit more refinement, especially in the high end. So the best ones are very good. If sound quality is important to you AND you're committed to redbook then these are worth seeking out IMHO. The SHM cannot turn a sows ear into a silk purse. To me, SHM is not revolutionary but more subtle in effect. As always, I would suggest checking a few out and forming your own opinion.
Agree with Hooper that the prices on these are a little out of line but then CDs in general are more costly in Japan. So adding the SHM premium onto already higher prices makes them around US$25-$27 not including shipping which is also high. So US suppliers have to ask somewhere in the mid $30s or more. And of course, exchange rates come into play.
As far as purchasing a SACD player or not, the existence of SHM-CD would not affect my decision one way or another.