I have a few, well actually a lot of problems with the PECS method of "communication". I dont know why schools use this system for kids who are able to make vocal sounds. For our boy, our SLT was insisting on using the PECS cards. Our boy vocalised constantly and now he is starting to talk, and is using new words every day. I feel that if we had used the PECS cards it would have been just one more unecessary step towards actually talking. What would motivate a child to talk if he can easily get what he wants by handing you a card??
Thats my thinking on it anyway and our experience of pecs has been negative. Again, the "recipe book" approach that all autistic children might benefit from PECS, or Makaton, simply isnt true. Our kids are so different.