@peregrino Thanks for reaching out!
Based on the sizing guide listed on the Salomon website, the difference in the length of one's foot when going up a half size in their shoes is .2", which is right about 5mm. We're going to tag a few of our shoe experts here, @REI-PearlD and @REI-JuliE, to see if they can provide some additional insight. Another option would be to set up a virtual outfitting appointment with one of our green vests with experience fitting shoes.
Hopefully we get your questions answered soon, thanks!