Catholicism gets strong Protestants.
ex-Catholics make the best MORMONs.
http://mormon2catholic.wordpress.com/2006/01/28/catholics-make-good-mormons-but-do-mormons-make-good-catholics/
And yet, I know many ex-RCC members who did not become Mormon or JW or even Adventist. They can make wonderful and generous Christians when not enslaved by a cult.