The bindings definitely fit the black boots better. I had a similar issue with my Flux bindings. I had 10.5 Salomon F22s which are a reduced volume boot and my medium Flux bindings fit them perfectly. But now I have Celsius Climate boots and they are not reduced volume. They still fit in the bindings, but just barely. I actually have to flip the discs and set the bindings back a notch toward the heelside of the board to get my boots centered, which judging by the pics you'd probably also need to do to center those red boots. Not ideal and they look a little wonky, but I honestly can't tell any difference in the performance.