Replying to Ski Length Question

Ok, I've decided to go back to skiing after 10 years of snowboarding. Now I've been doing some research on skis to get and I think I'm going to get the PEs, but I don't know what size to get. I went to Firehall Sports and they recommended the 159's but said I could probably get away with the 169's. The thing is, I've been thinking the 179's were the right size.

I'm 5'10', 190 lbs and I'm pretty aggressive. I want a twin tip that will be able to handle all conditions (bumps, park, groomers, pow) and be stable at high speed. I will be skiing mostly at blue this season, but I will probably take a trip to whistler where I'll spend the majority of my time hiking for pow.

So my question is, what is the right size? And is the PE a good ski for what I want to do?