Definatly do not be scared of the length. I spent quite a bit of time riding whistler yesterday on the 188. Im 5'11 170lbs. They certainly did not feel that big, I certainly would not want any shorter. The rocker in the tip is pretty long so they ride at least 10cm shorter in the park. I never once noticed the length when jibbing about on them. I took them through some deep powder and the length was perfect, in the deep snow you use the whole nose so effectivly you are getting a ski in two lengths. It feels shorter in the park but rides like a longer ski in fresh snow. They were incredible on the had pack too. I was ridding Dave Murry and got way over 110KM per hour on them and they never felt unstable.
Honestly one of the best skis I have ever ridden. I will be getting a pair of the 188's as soon as I can.