Meh. Frankly, I don't really trust drives with built-in encryption. Many of them have poorly-implemented algorithms (some actually just use XOR... yes, I'm serious), and I have no way to verify the operation of the ones that do claim to use more advanced crypto.
I tend to trust software crypto a lot more, esp. when it's seen the level of analysis that things like Mac OS X's encrypted images and TrueCrypt have.