Replying to Armada ARV 86 first twin tip sizing

So I'm looking at the Armada ARV 86. I can't decide between the 163 and 170. I am 5'7" 150lbs. Intermediate/advanced type III skier. Never used twin tips before. The skis i've used before were Head Instincts at 170 and they felt a bit cumbersome. The other skis i used were some other Head rental skis at 163, i felt more nimble and I had more fun. Also had no problems at speed going down the blacks.
How much difference is the twin tip and rocker combination going to make? Will the 163’s feel much shorter? Especially closer mounted to center? Probably -2cm back.
I’m interested in trying to get into the park. As of right now my typical skiing is on hardpack, looking for every jump i can find. I don’t care as much about top speed, but I want to be able to handle some occasional charging. The runs here are just not that long so i like to try and take my time and play around rather than fly down and get back in line.
Oh also I’m in North Carolina, skiing sugar and beech mountain mostly. So no powder. 86 is all mountain for me. Realistically going about 1 or twice a month.