I agree that thinking that you'll spring an amazing question on a JW that they can't answer, will get them out, probably won't work.
But from my own experience, little annoying truths might eventually make a difference. Maybe I shouldn't say annoying but disturbing.
I'm presently working on a "sister" at work. She knows that I don't believe it's the truth anymore but has that duo thinking going on. Yes it's ok to talk to me as long as I don't discuss scriptures and maybe she can help me....
When ISIS was going around destroying artifacts and buildings, she lamented over the loss of art. I said well, they think of them as pagan. The Israelites went around destroying temples and art too. Then I shrugged. ISIS is just doing the same thing I said. Deer In Headlights Stare.
ISIS throwing homosexuals off the building - Israelites gutting women and children.... Stare.... She didn't talk about ISIS after that.
It may never get her out, but there may be other incidents she'll experience that will cause her to reflect on these disturbing examples and her view of the "truth" might change.
See for me, the Dateline show from 20+ years ago and an elder saying at a bookstudy "we don't need to tell the truth" (meaning we could lie) were saved up for years until other things happened.