"The .270 has the advantage of a relatively flat trajectory, while still packing plenty of punch. The .30-06 has the same general configuration and powder load, but it pushes a bigger bullet, so the trajectory is a little loopier"
Not true. A 130gr .270 has a ballistic coeficient of around .380. A 180gr .30 goes over .450. This means that the .270 will bleed velocity at a faster rate and have more drop at longer ranges. Plus, the much higher secional density of the .30 caliber bullet will result in much greater penetration. You have to use a 150gr bullet in you .270 and drive it over 2800 ft/sec to come anywhere close to the '06. AND - the 30-06 is just getting warmed up with 180 grainers, you can buy factory ammo loaded with 220's that make the .270 look like the light game round it is.
Bullet: 150 Gr. Winchester Softpoint
In the .270, drop at 500 Yards (200 zero) is -44.1 inches.
In the .30-06, drop at 500 Yards (200 zero) is -51.9 inches.
(Source: Guns & Ammo, 2005 Annual Buyers Guide pp. 152, 161.)
The .270 does push smaller bullets, and is more appropriate for light game as you suggest. But even when the bullets are as similar as possible (Mfg, grain, type, as above), the .30-06 does seem to drop more. Which was my point.