I am sure the instant fade is better if you can deal with all your 'friends' trying to find out why you have stopped attending etc. If you can deal with that without slagging off the organisation you will get away with it. However it is very hard not to say something to someone about your true feelings.
I took the slow route as I know if I confronted the elders or others I would not be able to stop myself telling them exactly why I left and all the things I now disagree with. My son is still in and I need and want to have a normnal relationship with him.