The .30-06 gets about the same velocity from a 180 gr bullet as the 7mm Rem Mag does with the 175. The.284" does have a better ballistic coefficient and sectional density than the .308", but at most reasonable distances the difference in trajectory is small.
Of course you can simply load the 7mmremmag with a 160gr bullet that has more muzzle velocity,and a greater sectional density than the 180gr out of a 30-06.The result is an extra 200fps or so,flatter trajectory,and as good or better penetration with similar bullets.