Just a FYI for grafters -
I spoke by e-mail to the head of Penn State's fruit tree program today. I asked him if water sprouts were a good source of scion material for grafting. He said yes they are fine as long as they aren't coming from the roots. Those are suckers and may not give you the same type of tree you look to propagate if it's a grafted tree. In that case you would be duplicating the rootstock. If it's a seedling tree, a root sucker will give you the same tree as the one you cut - or dug - the sucker from. He suggested water sprouts from limbs or trunk that are at least 4 ft. or so above ground and about the thickness of a pencil. So - grafted tree or seedling tree, you can't go wrong with water sprouts cut from say, 4 ft. or so above ground.
Just a bit of info from an expert source for any of us that like to graft from seedling crabs, or other roadside gems we happen to find.