Well, I can't say as though I've helped anybody leave (that I'm aware of), but I've helped some who have left feel better about it.
I've shared Crisis of Conscience with both my neice and my aunt. One of my neices had left as a way of getting out of the home. She moved out of my sister's house and in with a guy a couple of weeks before turning 18 and subsequently married him. The strictness of her father drove her out of the house and out of the JWs, by extention. But she always kept thinking, every time she hears about things like 9-11. Were the JWs right? She was living in guilt and sometimes fear of Armageddon. I talked to her to assure her she had no reason to fear. I also shared Franz's book with her so that she could read what that religion really was.
I also found out an aunt of mine had left the JWs. I hadn't talked to her in about 10 years and we reconnected via e-mail. I was afraid she might brush me off after finding out I was no longer attending meetings, but found out she wasn't either!!! She said she got fed up with them taking such hard stances on things and left somewhere near 10 years ago. And her son is an apostate. I told her how Franz's book helped pull me out and said she'd love to read it and had ordered it.
So, while I may not have helped anybody leave, I may have helped those who've left feel better and prevented them from going back.
In my family of parents, siblings, aunts, uncles, grandchildren, grandparents, but not brother-in-laws, I count 14 total blood relatives that were once JWs. My parents were the first. As of now, 2 died as JWs and 3 more are still JWs (my father and sisters). All of the rest left (9 of 14). And from the sound of it, one of my sister's husband is inactive but still believes. Her daughter DA'ed. Reports from her daughter say she isn't living an exactly clean JW lifestyle (she buys x-mas presents and dresses her granddaughter for halloween). So, if I ever get a chance to have a heart-to-heart with her, maybe I can help her see the light. But for now, I try to keep religion off-limits with them all. If they want to believe, that's their perogative. And if they want to question (and I can only hope they will), I'm here for them.