truly, for a twin tip, since a lot of the ski is tip and tail, your ski should be near the top of your head. but ability has more than lots to do with it as well.
i think its funny how every comment so far about their skis being taller has been a park ski. if i buy some pow skis next year they will be about my hight hopefully, right now im almost 6 foot and ride 171 for park though so there pretty short in comparison.
im like 154cm feet tall and i ride a 165 center mounted. if you think about it that way its not that much more in the front and the back then if i had a pair of 150s.