There are many people who have left the Messianic movement and returned to real Judaism. However, it is hard to tell this by the Jews for Jesus website. They still have articles and stories on their website written on, or about, people who have long since left the Messianic movement.
For instance, you can still find Ellen Kamentsky on their website. Ellen is well-known for having written the book "Hawking God: A Young Jewish Woman's Ordeal in Jews for Jesus", in which she rips the dishonest practices of Jews for Jesus. This book was written back in 1993! You would figure that after more than a decade and a half of having left the movement, Jews for Jesus would remove information on her from their website but they have not.http://www.sapphirepress.com/hawking/
The same can be said about Jeff Neckenoff. Jews for Jesus still has articles on Jeff Neckenoff on their site yet he has been out of the Messianic movement for many years and runs a counter-missionary website, www.bethgoyim.com
You would figure that after someone left the Messianic movement (and are working quite hard against the Messianic movement) that Jews for Jesus would take them off their website. It would be logical to do so, but Jews for Jesus has not taken this logical step.