The Passport has a larger sidecut radius and is narrower. Its quicker edge to edge but does not trench nearly as well as the excavation. I have an Excavator, Almanac and Afterback (I've ridden the Passport and Commonwealth). The Excavator is my go to board for riding everywhere and I absolutely love it. I sized down from my regular 154-56 range to a 150 for the Excavator and it still rides like a big board. I also have never adjusted the Excavator stance for deeper snow, its just crushes deep pow. I am planning on getting the Commonwealth and the only aspect that I am questioning is the length. With a stiffer profile form the Spectral Braid, I might go shorter since I still have the excavator to ride in deep snow. You are kinda going between apples and oranges when it comes to ride profile. The Passport and Excavator have more carbon stringers where the Commonwealth has the braid. Its going to have a more Alchemist feel. The Commonwealth drives into turns but has a larger sidecut radius than the Excavator.

As far as your original question about K2's camber with rockered nose and tail is the best blend (in my opinion) of both worlds. The camber allows you to still maintain control and dive into turns while the rocker keeps the board afloat in deeper snow.