Terry, you found yourself a hobby.
If you enjoy it... if it stimulates your mind... if it holds your interest... then go for it. Who are we to tell you what to do with your hard-earned retirement?
That said, if you are trying to determine whether such a book as you propose has a solid chance of success, Mormon and JW comparisons are a decent place to start. But why stop there? You could next research Scientology (assuming that they don't send someone to "convince" you *thud* *whack* to stop) or any number of other fringe groups and include the similarities and differences in their recruitment techniques.
You could even include groups like Amway and Shacklee and Tupperware.