I wear usually a 10.5 shoe size and have size 10s in the hi-standards but they are a half size to big. Iv got the wiigs in a 9.5 and they fit me perfect. I would try and go some where and try them on if I could but I think all of vans boots fit somewhat the same in terms of size but I am not 100% sure about that.
Also hi-standards are really soft for snowboard boots. I think there like a 2/10 on vans scale and vans boots seem to be softer overall than other boot companies.
strange...i've worn a size 9 shoe for a long time. i own a pair of size 9 wiigs and tried on the hi standards in 9 at the store and that would've been good for me as well. the vans in general fit a normal and narrow size foot. if you have a wider than normal foot than that might be the reason some people are sizing up. if this is the case, the vans might not be the best boot for you.