I don't get the NS short ski fixation. I feel like everyday there's at least two threads made by people who are 5'8"+ and want to ski something shorter than 170.
Long skis give you stability. Yeah you might not be able to butter as easily and spinning on/off rails may be a little harder, but what you'll gain seriously overpowers the inconvenience of getting used to a longer ski. You be able to take landings deeper, ski faster, and generally land things easier. It's more material to land on. Especially with park skis...symmetrical construction and mounting true center makes skis ski way shorter than they are anyway.
I'm 5'9" and I ski a 181 in the park, 183 in pow. Going down to a 177 this year (afterbangs) but ill probably still take my 181 moments out for jump sessions.