I was waiting for an idea to pop up and noticed you mentioned ATXRaspi in another post, so i thought yeah it's possible, but the prices are *insane* for some of these solutions. I did manage to find this one that is very tempting, but wanted a second opinion first?
I forgot to mention it's not about power savings for my device, but rather my NAS seems to not want to sleep with the pi constantly sending a keep alive making the hard disks spin.
I still can't quite understand why they can't make something so simple without corrupting your card at the same time!