Beat the game couple days ago. Also the bonus bosses, including the ultimate boss (who negates quicktime). Halfway through my new game plus and trying out new paths.
For anyone needing advice, focus heavily on magic early on--build the research center and get those fusion spells unlocked, or you'll regret it down the line.
Also, there is some game breaking loot to be found in the bonus dungeon that unlocks after Gerard's era. It also seems that any battles in the maze of memory don't go towards moving the enemy rank up, so it's a great place to burn though battles while your r and d guys make new toys.
Oh that's good to know. I've got access to the Maze, but figured it was end-game enemies and the like. I'll take a crack at it.