Replying to Rockered Ski Length

I am getting a pair of hellbents this season to be used in the park as well as the bc (half and halfish). I normally ride park skis +/- 180cm. I've never ridden a pair of rockered skis and have heard to definitely buy bigger because of the effective edge and rocker will make them feel short. Because of k2's sizes being 179 and 189... should I really bump up to the 189? That seems long to me, like too long to be swinging around in the park. Can anyone shed some FIRST HAND light on this situation please.