I picked up a couple of Paw Paw's from Ken Taylor at Green Barn a couple of years ago and they are doing fine. Had some rabbit damage on one of them that turned it into a stick last winter but new growth this spring and all is well. I live in Montreal, Canada and have had no issues with the cold which can go down to -30 celcius some nights. I planted them in partial shade in an area protected from the north east wind. They were pretty small when I received them and are a couple of feet high now - most of the energy has gone into roots, hoping to see it start to take off next year.
Mike