In one of the recent patches they improved the enmity (hate) generation that PLD gets for using flash. On top of that the PLD flash also blinds, which is a very useful debuff when it comes to survivability. So in summation flash is great at gathering enmity, just not so much on the WAR. I use flash mainly on downtime from pacification with WAR as he has extremely low mp. Overpower is still my bread and butter with WAR though.