If you don't already have problems or uncomfort in your knees, you probably won't be able to tell much of a difference. I couldn't. If you're knees are giving you problems though, a lot of times the canting will ease the pressure a bit.
Canted bindings definitely have a noticeable difference in reduced knee pain/fatigue and general comfort. How important that is to you probably depends on what kind of shape your knees are in. The footbed makes a difference as well, as the soft, minimal footbeds on ones like the NOW line are not canted but just as comfortable if not more so than canted ones I've owned like the K2 Formula.
I have noticed people talking about canted bindings and the degree you can have. I was wondering on how to change the degree of your footbeds and padding. Do the come with a couple sets with different degree or is there a way to adjust the setting??
Depends on the binding. My company's have canting, but it's not adjustable. I think union makes some that have interchangeable pads. I'm pretty sure Wrathful (might have been somebody else here) has macgyver'd his own canted footbeds.
if you are unsure but would like to try canting check out rome 390 boss or targas as they both come with pads that have canting and pads that don't. I like canting, it took me a few times to get used to it but now i really like it.