i own a pair of burton ambush boots...so i will give you my 2cents here
i wear 11.5 size boots..but i got a 11 burton ambush just in case cuz its a soft or mid soft boot if you like...
the boot is tight and by that i mean 29.5cm is not as lets say nikes 29.5cm its shorter so the for me its kinda just a little bit short..i thought its gonna be ok after a few days but that didnt change...but dont take me the wrong way this is not that big of an issue
on the other hand from day 4 or something around that time boots somehow lost a lot of support that they gave me until that point,and by that i mean around the ankle...they just felt way looser than on the first three days and its not something that i like
looking at my setup
roto ct,union forces and burton ambush...the boots is the first thing that one day will be changed
dont take me wrong great boot all the way just my experience,could be that i have narrow feet and small ankles if you know what i mean,im 6'4'' 215 pounds but not big boned so i think that is my issue,hope i helped