I am interested to learn about ankle movement in the boot. I have the Lange RX120 and it fits pretty tightly. I have been told by a bootfitter in Canada recently that my boot was too tight around my ankle and this would restrict my ability to use the foot muscles to effectively turn. As a result the boot was punched out a little around the inside ankle bone and also a little in front of the ankle. The boot is still well fitting and I don't have heal lift. I can however now really feel my foot move to the inside like it is rolling over to the big toe edge. I think my foot is pronating? The foot bed I have does have a little 'give', it is not a rock solid effort.
I have only skied in them for one day and I am not sure if this is really a benefit or not. When in a carve turn it feels good, I can feel the inside edge of my foot hard against the boot but the change in tightness is weird and not what I am used too.