We were just talking about this subject last night as a couple. We'd just found out that a married couple we liked, respected, and classified as of a higher intelligence than the average JW, recently and dramatically "dropped off the grid". Apparently they encountered something regarding the Org's history/practices that gave them pause. No one seems to know anything more because everyone is being told by elders to not ask them their reasons, or listen to them if they reach out to you. Our close friends who gave us this update are "intelligent", but their response is: "we don't want to know; we CAN'T know what it was" (ignorance is bliss).
As a couple we discussed how, not that every "intelligent" JW is leaving, it's that those that are leaving are the "intelligent" ones and that the remaining intelligent ones are coping by sticking their collective heads in the sand/fingers in their ears. My other half who is not (yet?) in exactly the same place as my mind, expressed quite a bit of concern over what that meant for those of us who are still "in".