I actually haven't tried that trick. I will confess though, I've been playing in fairly linear fashion trying to see where things are then I plan on going back through to snag up all of the side quests I've missed on a new game. Right now, I'm about to go on to Oerbakartoffel said:Gran Pulse is where it's at. Have you tried the death spam trick against the big turtles yet? Set up Vanille as your party leader, summon right away, blow your summon's load right away with just the final attack, and then while the turtle is still staggered, you have Vanille fire off as many death spells as possible until one lands and takes it out.
Side quest #55 is also worth doing early, using the death spam trick. The reward is an item that gives you double CP when equipped.