Heli Packs are smaller, but in my opinion, better. The pro has all this added shit you dont really need, and you pay up the ass for it. Go with the heli pack, it'll carry skis, gear, shovel and water.
My one regret with mine is the hydration sleeve. Dakine boasts that it'll keep from icing up so you have water at all times. Mine never freezes unless it's 32 degrees or below. Its bullshit.
Oh, and the dakine reservoirs are shit. The quick disconnect thing is a great idea, but mine always disconnects when I'm riding. Go with a platypus.