Played hunter a lot. Look at stats. Went flawless in trials with it first too.
You have the range and shot travel advantage. Use it to your advantage and dont just sit in one spot when you do.
Jumping is DEFINITELY not enough, as hammers can very easily hit you in the air with proximity det. Due to limited lateral movement while in the air it doesn't matter if the opponent is close or not.
Jumping is not enough unless they lack skill. It has nothing to do with jumping "too slow", if you're in the air you are in the air, there's nothing you can do to increase your speed. And once you are there you have to hope for the best because the proximity can still catch you easily. It's out of your hands, it is entirely up to the Sunbreaker to screw up for you to survive.
In fact, any method to counter a Sunbreaker that doesn't involve a super is always their battle to lose.