With canted footbeds, the options are there for you to find what's most comfortable for you. There is no specific use for the levels of canting. Find what is comfortable for you. This will mean that you are going to have to bring your tools and footbeds to the mountain and spend a day trying different combos to find the most comfortable.
Whatever you want to do, do it! I set mine up with more cant on the back foot, forcing me (in my mind at least) to keep the proper stance = more weight on the front foot. I'm gonna play with it next time I go riding. It finally started snowing here but stupid work gets in the way many times.
I have it setup like this: I ride regular with 20 and -10 or something like that.
Left binding: 0° in the rear part, and 2.0° in the front. Rear is full 3.5° front and back.