I have no experience with the Jac off masturbator.
Have you looked at the Tenga Eggs? They're a very popular masturbator. My boyfriend's first masturbator was a Tenga Egg with the spider design. Unlike the Jac off, the egg stretches to cover the whole penis. The egg only lasted a couple of sessions until the top ripped open, however. He had a lot of fun with it solo and with me. I really loved using it on him.