Replay value for Tears to Tiara

Have been a while since I finished the game, the voice messages tell that you should play the game again, when you save your game after finishing the last battle hints that there are benefits for saving them, but what you get for replaying the game in a new difficulty level?

I don't really know but did you get to finish the hidden quest?
(the Leaf Tower)

It's hard as hell BTW, if you chose normal, you can finish it with LVL 80 chars. If you chose impossible, well, it's impossible.