I am less positive then you are about letting any one peruse my child's pictures. The issue is not just about using the picture to masturbate to. It is to me is this person in my area? If so and he sees what he has be lusting/worshiping over walking down the street will they try to rape them.
Child rape is common enough and it is about opportunity but do you really desire to add to the formula prelusting over your child? Not me, if I post a picture for a family member to see it is locked up tight with long passwords. Mostly I just mail a disc to them or an e-mail. All of my family have been warned not to post our children on the internet. Yup you beat they guy up after he kills little Johny but little Johnny is still dead.
I think that there is no safe computer in the world if it is hooked to the internet. I have many pictures up in flickr where my extended family can see them. I have family stretched from the east coast to the west coast and it is just easier giving them access to my account. I know they are not going to post them elsewhere. I know where all the sexual predators live in my area and the neighborhood I live in is very active on keeping them away from my area. The nice thing about my kids is the youngest is 14 will be 15 this summer. So they can better defend themselves.