I remember very clearly in my "hearing" (I've forgotten the term) that the elder reverently spoke of how unified the witnesses are and that they stand politically apart from the world and that is how that showed them to have the truth. I looked at him a little squiff and said "hold on, didn't Jesus say that you will know my disciples by the love they have amongst themselves?" ....
I'm sure there are breakaways, but that they are small and unknown.