shorter skis are less stable, be it on jumps, landings or just all mountain skiing. once you get used to long skis you'll be a lot more confident with your skiing. and yea, i guess technically shorter skis will be more maneuverable, but i'm not sure what you have to maneuver around that much when you ski that makes u need a smaller ski. so like i said, i'd get a least 171 if i were u.
be glad you can have a park ski thats big enough, i'm 6'3'' and i think my 179 PEs are too short, but it's the longest size they make.