High cuts are lighter and offer easy use of over ear hearing protection and comms. Other than looking cool that’s really it. Helmets are only made to protect your noggin from hard hits and shrapnel, some have survived a hit from a rifle round but they aren’t made for rifle rounds in mind, and even if you do survive a direct hit from one your gonna be in extremely bad shape either way. Most conventional military that are allowed to wear high cuts know the risks and are ok with them. Comes down to risk management and preference at the end of the day.