"Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of the soulless conditions.
It is the opium of the people." Marx
I think everyone here would agree, Simon, that while they were in, they were typically "all in." They accepted the doctrine, even those aspects of the doctrine that made little or no sense because of the "package deal" that Jehovah's Witnesses offer. Other than those raised and indoctrinated to believe (or forced to), those that accepted the doctrine did so, typically, because they were disillusioned with something or other. Their faith in their own religion, their faith in society, their faith in commitment, something arose in their life that moved them to become susceptible to the peculiar nature of JW's. They wanted to believe, they wanted to belong, and learning about "eternal life" and being "special" was exactly what they needed at that time to answer that particular longing.
So, when you ask, does any of this stuff work to get people out? I would say typically no. However, just as there existed susceptibility to move one to accept, there must also exist susceptibility to move one to question. When one starts to see through the "veneer," as Franklin Joseph Rutherford so aptly called it back in the 30's, then the dulling nature of this particular "opiate" loosens its grasp on the believer and they either move to agnosticism or complete disbelief in God.
Just some thoughts,
SOP