It's great fun but the tank AI is frankly shocking. I've gotten significant offence/defence upgrades for my DRG and CNJ so far, but I'm stuck with Independent IV for the GLD. The very first pull is significantly more challenging/annoying than anything else in WP, Tonberry King included.
Simply having the Tank more willing to allow adds to come to the group before charging them would fix the majority of the issues there (including the comical behaviour on the final boss).