Radiant Historia is probably the best use of time travel as a plot point in a game. It was hard to take FF13-2 seriously after playing it.
PS those who had to grind in this game were probably the people who kept using the same team all the time. That's not how you play a JRPG. The bosses all have weaknesses to different party members.
I beat it at 50/49/49 or so with Stocke/Raynie/Marco which while not underleveled I don't think is overleveled either.
I beat the game at level 35 or so, so I'll let that speak for itself. Stocke/Eruca/Aht was my team for the final boss.