I haven't found this to be true at all...
As a matter of fact, I've found it to be just the opposite of what the article states.
For example: When I have my wife in the car, and she's talking to me, I find it much more distracting because she insist on trying to point things out to me. Or, she'll try to tell me how to drive - annoying as f**k really.
When I'm using my hands-free, I just cruise along listening to music, or chatting on the phone with little distraction. Also, if I do need to make a call while driving, I just use activate the phone's voice recognition for that, with one simple push of a button on my lapel, and keep my eyes well on the road. It's easy as...
Granted, I'm very safe and experienced, with about 30 years of driving under my belt. I don't tail-gate, weave in and out like a lunatic, or speed by much. I've only had two accidents that could be considered my fault, and no one was ever injured in them. And, none of those accidents were caused by cell phone use, because they both occurred before I even owned one!
Paris, well, because the little slapper likes to drink and drive!