Having played all three roles, DD is the most complex to manage. I think Yoshida honestly went overboard with the damage dealer complexity and needs to tone them down a notch on a case by case basis. Ninjas and black mages are perhaps the most polarizing in terms of player skill. I've had multiple FC mates commenting that a ninja is either really good or really bad, but never in between. Having played ninja to 50 I can see why.