I've been suspicious of claims by proponents of consumer driven health plans that they will encourage more responsible and cost efficient purchasing behavior by patients for their healthcare needs. Individuals simply don't go out and shop for medical care in the same way they shop for a car or television or pair of shoes. The choices are infinitely more complex, out of the control of the consumer, and incapable of being intelligently compared with one another. I just don't see how the idea can get close to fulfilling the claims its proponents make for it.
The Center for American Progress has a recent report on CDHP that reiterates some of my own skepticism and much more.