CIO (Cry It Out) Helpful or Harmful?

My husband and I do not subscribe to the CIO method.  We are attachment parents.  However, I will be the first to tell you that as a daycare worker I used CIO all the time. It has never felt right for me as a mother.  When I hear Avin cry I feel it in my heart and soul.  After a couple of months I could even tell what his different cries meant from down the hall.   We have had people tell us multiple times "you know it won't hurt that baby to cry for a while".  My response to that is "well it might not hurt him but it does hurt me, sorry".  In the past couple of weeks I've come to understand that I have been wrong, extended crying can indeed hurt your child.  I'm not trying to say that anyone who uses CIO is abusing their child but studies have show extended crying to have ill effects on children.  I found the information presented in this blog article very startling but helpful: http://www.lepetitowlet.com/2010/04/dangers-of-letting-your-babe-cio.html.  Every parent has to develop their own routine and find what works for them.  I wouldn't dream of saying the methods my family uses are what would work for any other family.  I just encourage everyone to educate themselves on the subject.  Don't let others pressure you into letting your child cry it out.  Yes, babies can cry, but why should they have to?