I just bought a pair of Thraxis in a size 10 and after having them heat moulded, they still fit smaller than the size 9.5 K2 boots I rode last year. When I hold them up against my old Raider Boa boots the Thraxis are actually physically shorter in size then the old boots but are labelled half a size bigger. I couldn't get my foot into a 9.5 pair of UFOs I tried on this year. My suggestion is to try them on before you buy them. I haven't tried this years Maysis so I can't compare.
I'm not sure how much they will pack out after the heat moulding, I've heard mixed stories on this from various people. My toes are comfortably up against the front but they are not crammed into the front of the boot, I'm not taking the chance on them not packing out a ton.