I was giving this a little more thought yesterday, thinking about all the JWs I know that left and what classification they might fall under, and I realized there is a small subset of former JWs not captured by any of the four categories.
I wonder if this was a local phenomenon or whether it's widespread, but there were a few folks who showed up, made a splash, got into pissing matches with elders, decided the JW religion was too small to contain their talents/wisdom, and either faded away or were shown the door.
Most of these folks came from charismatic churches and had a tract record of church-hopping. Other were just Class A a**holes and thought they were always right and should be able to run the show from the get go. Few people were sorry to see them go.
This is by the far smallest group I can think of.