[B767Driver]

Your answer won't lie in the horizontal airfoil (the wing) but in the vertical ones (the props). A turboprop is mostly limited to such a low mach to prevent the propellers from going supersonic (specifically the tips). Mach tuck won't be an issue.

On a lot of the racing airplanes you will see shortened diameter propellers that enable the airplane to go faster without losing efficiency to mach effects at the prop tips.