Many race boots nowadays appear to have some cut markings near the tops of the shells - the inner leaf, that is closest to the shin/tongue. Cutting the top 1-2 cm will effectively lower the front of the shell.
What exactly is the effect of cutting or not cutting the plastic there? Why would one choose to do it or not?
Of course, you can say "try it". The problem is, obviously, that once you cut it ... there is no more "trying" - it's done for good :-)
If I am not mistaken, some Dalbello Scorpion models come with the opposite, i.e. a "build up" plastic plate that you can attach to the front, but I don't have these. Nordica, Lange, Head (?) etc just have cut markings.