Logan:
I think you are vastly underestimating the psychological draw of the Watchtower philosophy. Your numbers are outrageously inflated. People stay JWs more than just for the fear of disfellowshipping and shunning. Surprise, surprise -- a lot of them actually believe
That is very possible about the underestimating, after all I spent 35 years in it. The last several years tho' I was afraid to 'speak my mind' any time I did, I was beaten down by the other fearful people saying, Oh, you shouldn't be questioning the Elders, FDS, the GB, etc. I could SEE the fear in their eyes...
As far as my own experience about the 50%, as I said, this is from my memory and my particular circumstances... it is not inflated at all. However, like I said, it doesn't mean anything because it will not hold up to an average of everyone else's experiences.
The 70-80% may be wishful thinking on my part, however once JW's could start openly questioning doctrines and practices, I believe they would quickly become disillusioned. It would be VERY easy to stop the now required 'Field Service' and 5 meetings a week...