I've heard about this, and IMHO, like the hybrid cars... well... crap
Its one more of those silly inventions we can all forget about.
SSD will be falling prices quite fast, just because today we have to pay for research and new factories, and the customer pays the price, the factor of not having much copper, magnets, motors and controllers, will in around 2 to 5 years, make SSD's so cheap that we'll wonder why this was not the answer in early computing stages (around 30 years ago) where the first nand based memory chips were patented.
Curious, yesterday I saw one Top Gear episode where Jeremy puts all the world crap into the hybrids, slow, costly and really bad vehicles, this SSHD goes into the same pit.
Its like sex, whats the fun (IMHO) of having both genders, bah, all the fun is gone.