The fact of the matter is, their necks just aren't strong enough at age one to protect them in a wreck. I urge everyone to do their own research and make this decision for yourself. For us, it was a very easy one. Check out the following videos and links. I'm not trying to sound like a know-it-all mom... I just want the information out there so you can make your own, educated decision. A friend brought all of this to my attention and I just wanted to pass it along. :)
This one's not in English, but you'll get the general idea.