Sheridan summed it all up very well. +1

While the .270 is flatter shooting than the .30-06, no rifle is a laser beam of death. It's simple physics, with the bore at zero degrees elevation, the bullet will begin dropping immediately upon leaving the muzzle.

The desired result here is a hit in the target's vitals. Knowing your caliber's performance at varying ranges and practice, practice, practice can overcome any advantage one might perceive coming from a "flatter-shooting" caliber.