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.
Interesting comment. I checked with a Union rep a while ago and he recommended the L/XL for my size 10 Fargos. Now, those are bulky boots, but if the M/L supposedly fits size 10-10.5 Kaijus perfectly it should be able to take my Vans, no?