id go center because in the future it would annoy me if i was in the park and i kept blaming shit on the fact that my ski is not true center.
and also, you can control a center mount in all mountain terrain, ive been doing it with my k2 PE's and now my ON3P j-mos. thres a learning(comfortability) curve to it. But ultimatley if you ski 50% park your going to want that stability and even-ness..
I mount all my skis true center, youll ski fine in powder and its a hell of alot better in the park