If the index is reconstituted based on a committee vote then you have absolutely no way of knowing what will be added or removed. Look at the historical changes to the DJIA. Its components are decided by the editors of the WSJ. Citi and GM were dropped from the index after their fall from grace in 2008. Any index mirroring the DJIA would have needed to sell its Citi and GM exposure and add the new components.
You want an index that has a transparent process for removing and replacing index components so that you will be able to trade accordingly.