R.L.
You're probably going to get a lot of opinions with this question. I personally think if the binkie is only to sleep, then there really isn't a problem with it. My daughter used it until about 1 week after her 3rd birthday. She never went in public with it, she ONLY got it for nap time and bed time. I thought it was going to be awful taking it away, which is why I waited so long to do it. We told her that her new cousin Natalia needed her binkie becuase she didn't have one. So one day we went to her house, my daughter put the binkie in Natalia's crib with her, and we left it there. The first night was rocky, but after that, she didn't even miss it. She was too happy to give it to the baby.