One more remark about appropriate length:
As an experiment for the uplifting of mankind and because I have a pathologcal obsession with owning as many skis as my closet can hold, I have taken a bold step. In addition to my notorious Rossignol Bandit XX's in 170 cm length, I have added a pair of Rossignol Bandit X, also in 170 cm length. I personally feel that 170 is the best length for me in each model . . . but here's the result:
These brother skis are alike in virtually every respect - same materials, same construction, same length. They vary only in width and slightly in shape. Having skied the single X only for the past two days and only on firm snow, it is clear, and even the most obtuse-on-snow can realize that the single X has markedly better edging, is easier to maeuver in short turns, and is more stable in both short and long turns and straight running as fast as I could go while keeping my lift ticket.
The point is, length is only one factor. Skis can vary by general stiffness, flex pattern, shape, and total base area on snow. The qualites that Arcmeister describes are wonderfully subject to manufacturing control with today's materials, constructions and designs. The "right ski", it would appear, is the one that best hears the skier "talking", and "talks back" most clearly with information the skier can use.