Just wanted to put this here as to a suggestion in making the story content re-playable, as too why? Well having story content related to a given area rather than just doing side missions and raid's I think actually add too the atmosphere of the game. Given that the voice acting on the English side can use... alot... of... work... no offense, its just... Wow.
(which is why I've switch the audio language to Japanese)
That out of the way, the story quests should retain their original rewards, maybe even have like a nightmare mode that gives more rewards, but the point is, I think it would be alot of fun to go though them again. Ep 4 was alot of fun, and same for the previous sets.