I've always been afraid of how self encrypting drives work, since it's really not transparent to the user what's going on. I'd be fine using it as an additional layer (since it's generally "free" from performance perspective), but I'd trust CPU-based encryption (with AES-NI) for bulk disk crypto like file vault, and then application-specific (or more "trusted" apps like gpg) for things which actually matter.
Yeah, the pressure of NSA demanding access on anything resembling HSM is obvious. Anything that's not open source has the potential to hide undesired behavior.
Also, more fun would be "cryptolocker" disk-based malware. The aspects of capability exist elsewhere today as mentioned in the article and cryptolocker's $15 million USD and counting.
Also also: is there any HIDS yet for checksumming various chipset/peripheral firmwares?