Thanks! Another question I have is how do you know if a binding is too big for the boot? I wear US Size 10 Vans Aura with L/XL Union Contact Pro. I have the heel loop set to 0 and the straps fit well and aren't bottomed out. I know Union says L/XL fit from 10.5 and up while M/L fits up to 11.
As long as your boots fit in the binding without being bottomed out and at the same time you can center the bindings you are fine. Not being able to center the bindings can be a sign that the bindings are too big. In that case they will produce more overhang on the heel side even on the most forward setting. Size indications are not 100% exact because most boots have a different size footprint.