This may seem lazy of me, but it seems pointless that a character who is high enough level so that doing a given quest on elite yields no experience must still do the quest on normal and hard in order to unlock it on elite.
Would it not make sense to allow high level characters who, if they get NO experience from a given quest set on elite, would be able to avoid having to repeat the quest on normal and hard and immediately be able to unlock it on elite?
Just a thought...