Just a small recommendation in regards to space in the shi/tongue area.
I have noted the same several years ago in all my boots.
For the past 5 years I install a second power strap which is NOT anchored to shell, but rather to liner top. It goes from very top of rear liner to top of front tongue.
This has two functions.
1. It reduces that space ( if not eliminates it ). Thus you get a better ski feel, better instant ski response, less muscling and more finesse skiing.
2.It allows for better control of upper boot pressure, with less "tight" ( or over tight) fitting.
How do I do this ?
I get power straps from other rejected ski boots or make my own.
I sew in strap with high quality top level thread.
Better skiing, Better fit.