I've ridden the Kaiju for the past couple seasons with the Atlas. I'm a 10, and the M/L fits perfectly.
Not sure what the commenter above is talking about with lack of adjustability? Grab some other bindings off the shelve. Union is as adjustable as anything out there.
How much if any did you have to adjust your bindings with the kaiju? Was it a good fit out of the box, did you have to just more than the straps