Although he told it to you in a rough manner, he is still completely right. I've said it before, but I'll say it again. I completely regret getting a short ski. And by short, I mean it comes right up to my head. With todays twintips and progressive mounting points, and skis with rocker, you really need to go longer. Sure it sounds scary at first but the worst that can happen is it makes you a better skier. I mean, stay within your size range that makes sense for your body, but always choose the longer, top end of that size range.
For instance, my height of 5'7" and 150lbs. my range could be from 165cm to 180cm. So I'll ride a 176 which factors in close to center mount, my height, and my medium weight which crosses off the 181 on my list. If you want your moneys worth, go long. I'll never make the same mistake again on my skis and am trying to help avoid people making the same mistake. Have faith in yourself, you will be able to handle the ski.
As long as that feeling's there, you're gonna keep coming back every year until you get that feeling and more.