It seems to me that the "rabid apostate" approach scares people off and even a JW's with serious doubts of his or her own, can be intimidated or shocked back into their safe little rut of cognitive dissonance , after an encounter with an apostate.
To me the best way is to quietly raise questions, not demand answers or put them in a position of having to defend anything, and let them know where to go for answers or another point of view.
It seems like a lot fo Apostate encounters with JW's are vindictive in nature and about the Apostate venting his or her frustrations rather than out of a true concern for enlightening anyone. I was far more inclined to look into the questions and doubts I had, on my own once I knew where to look.