Question about Shell size and sole length on FTs

So I have a pair of FT TW hot doggers from 11/12 and the size and fit is pretty good as of right now. I might get a bigger size next season because my feet grows. So i am getting my own pair of skis next year and if i get the bindings mounted at 310 mm(size 27,5) which they are currently, if i get a size 28 next year, is the shell the same 310 mm and more space in the liner, or is the shell longer? And if not, can you adjust Marker Griffons that little amount of length?