There's virtually no question that if Benning offered up Pettersen straight across for this year's #2 pick, that the deal would be done instantly. It's not much of a reach to presume that every GM in the league would regard Pettersen as more valuable than the #2 pick. As was said, he's played a year in the NHL and is an already highly regarded, as close to sure fire elite player at the NHL level as you can get. It's pretty obvious to see with his skill, IQ, vision, character and work ethic.
Every hockey pundit across the league universally agrees on this. He will almost certainly be winning the Calder this year. I would argue Shero would also do that trade for the #1 straight up. It has nothing to do with us as fans overvaluing Pettersen as a Canuck. That is Pettersen's value across the league.
It doesn't matter if you have choices with the pick. There is no player in this years draft that will clearly be as good, let alone better, than Pettersen. I'm not saying it's not possible Hughes or Kakko, or even another prospect will end up being a better player in the long run, but it sure would be a gamble at this point to speculate on that.