Fist of Havoc can shut it down, but the chance of doing so isn't great. The super is poor. You need to be right next to him to do it. He can throw a hammer at you from 50 yards away and get a kill. Nova is a better counter. As you say, Golden Gun won't kill if he has max armour. There is no real reason not to use a full armour build as a Sunbreaker.