Gayle - I agree that it would be a challenge to turn it into a screenplay that people could understand or relate to, but your "Firm" concept fits my idea, and I think you could run further with that than you suggest. I was actually thinking about how you would make it into a compelling film, but when you think about it hard enough, all of the elements are there. For example - how shocking do you think it would be for outsiders to see the portrayal of a group of men sat in a brooklyn office holding weekly meetings where they discuss intimate aspects about people's lives, i.e. stance on oral sex, homosexual adultery etc - the decisions of which impact on millions. There is also the power struggle where Knorr tries to cling on to absolute control but loses due to a series of events. I agree that Franz was a quiet and humble man, but I think an actor like Damon could portray these qualities in a way that is engaging.
You also have Franz's friend (can't think of his name now) who ferries people to and from the airport, and the truth is his life. Franz befriends him and they begin to have conversations together that contradict the society's teachings, however his friend is among those embroiled in the witch hunt and thrown out of the organisation while Franz is on his leave of absence. There's the undercover intrigue of the witch hunt itself, and the absurd way in which he was disfellowshipped for eating a meal with a disassociated person. The "riches to rags" story of moving from a plush bethel suite into a caravan on someone's land and doing manual labour in his 60s. You could bring things forward to the writing of the book and a form of reconciliation with the lies he was helping to spread while in the governing body, and the putting right of those wrongs (to an extent) with his book.
I'm not saying it would be easy, and it would require ALOT of thought and work. But just imagine the impact it would have it was ever made, and became a popular if controversial movie...