My opinion has changed about little guys throwing the CB. While I believe that thrown correctly it will not hurt their arms, the problem is that it is difficult for them to maintain the proper mechanics at a young age.
When it is thrown incorrectly it has the potential to be very dangerous. So, my son knows how to throw a CB correctly, but we put it on the shelf. He has plenty of time later for that pitch. He throws FB's and CU's. And he loves throwing a knuckleball.
Bottom line for me is, it's simply not worth the risk. JMO.