This quote in http://www.epicski.com/t/129521/closest-ski-to-old-mantra caught my attention :
Markojp is half right about your size. You're about average these days for weight, which relates to bending a ski at midsection. But you're 80th percentile for height, which relates to the leverage you can use to pressure the tip. So you'l want to think a bit about length when you demo. Might be better to go for a slightly flexier ski in your proper length (say 178-183 cm in the 90-100 mm range) than go for a really stiff ski in a too-short length.
I'm in a non-standard height/weight demographic (I'm short for my weight) and haven't seen a lot of discussion of how exactly these measurements play out, so this description really caught my eye. Tell me about pressuring the tip and when I need to do that - the only thing I can picture is pushing the tips down when I'm on the back side of a bump (front side? I always get that confused). I thought ski length was more about a tradeoff between stability at speed vs. maneuverability in tight spaces.