I was a little taken aback by the claim that the -08 is a flatter round than the Mag, so I checked my Winchester ballistics app. Loading both with 140gr Ballistic Silvertips, scopes zeroed at 200 yrds and checking terminal ballistics at 400 yds:

7mm-08
23.1" drop, 2,030 fps, 1,281 ft-lbs

7mm Mag
17.8" drop, 2,315 fps , 1,666 ft-lbs

While the 7mm-08 is an excellent ctg, the 7mm Mag is 5.3" flatter, delivers 15% more velocity and 30% more energy. It also experiences 3" less wind drift for a 15 mph cross wind (simply because it arrives 0.1 sec faster).

Comparing the -08 140gr to the .308 150gr silvertips (my app does not have 140 gr rounds for the .308), the .308 is 1" flatter even with the heavier bullet, delivers identical velocity and 7% more energy. Since terminal knock-down (TKO) is a function of velocity, mass and bullet diameter, the .308 also delivers 16% more TKO (25.8 v. 30.0, allowing for 50% expansion).