try to find the old one with the titanium powerband... 172 might be short if your not going to do park, take the 182 and just mount them as they are supposed to be (back from center...)
and most of all, your feet. Personnaly, tecnica is the boot that have the best fit for my foot. Go to some shop and try a lot of boot, thats the only way to know wich one is the best... and for the stiffness, only you know what you need...