Ex-gays, their eloquent testimonials, and the screamingly intolerant reactions they get from the GLSENs and PFLAGs of this world, are the magic bullet for killing the homo-promo movement.
There are many issues from which to argue against homosexuality and it can be overwhelming. I've tried to concentrate on the message of ex-gays for the very reason you list... The message of ex-gays brings light to the subject. Yes, they can leave the lifestyle!