RE: Harriers w/H9 Extra 330s question.
I havent been able to get rig of all wing rock with the Extra. I found a little spoileron helps (maybe 20 degrees) but a lot seems hurt. One technique that seems to help some is to slightly roll off of level and hold a little opposite rudder. "Loading" the model some seems to help lock the wings in. Its takes some practice to get it down, the inputs are subtle.
Alos try minimizing aileron inputs and throttle movements. Both will contribute to wing rocking.