I don't really main any class but I have used sunbreaker plenty in PvP. Compared to all the other supers, it has no cons, which is the problem. It has all the pros of other supers, range, duration, ammo, area of effect, tracking, max armour and health regen. All Bungie has to do is either remove the health regen, or decrease the armour buff to blade dancer level so it's atleast stoppable.