Uh... flatter trajectory, lower recoil.
I ain't no novice and that little M7 is easy on my shoulder. I've fired 375 H&H and goose hunt with a single shot 10 gauge. If I was a girly man, I'd worry about recoil. The .308 ain't squat for recoil even in a light rifle.
As for the trajectory, the .308 is good to MY limit, 400 yards. I won't shoot farther than that. Anyway, comparing it to my 7mm Rem Mag (you consider that "flat" don't ya?), the 308 has a maximum point blank range (3") of 273 yards. Zeroed at 232 yards, it is 14" low at 400 yards. I've made shots on coyotes at near this range. The secret is a good laser range finder.
A 150 game king from the 7 mag at 3150 fps muzzle velocity (the 308 starts out at 2773) is sighted in at 250 yard zero, is 12.9" low at 400 yards. See much difference here? Now, I ran the ballistics through my own exterior ballistics program which does not calculate Max PBR, but looks like it's around 275-280 yards. Hmmm.....lots a difference there, eh? Ballistic coefficient on that bullet is .532, on the .308 (a 150 Nosler BT) is .435.
Just to toss in the .257 Roberts....100 grain game king BC=.388...mean velocity 3147 fps... zero range 250 yards .... drop at 400 yards 14.67 inches.
Are you seeing something I'm not, here? I went through all this ballistics stuff big time 30 years ago, when I originally had a Timex sinclair computer with a 16K add on memory, then got a Tandy Color 3 with 125K, big time upgrade.
I finally came to the conclusion that it was all interesting, taught me a lot, but one thing it taught me is that there just ain't a hell of a lot of difference between the "flat shooting" calibers. Sure, you compare the 7 mag to a flat nose .30-30, you can see the difference. But, you're telling me that 2" roughly of extra drop at 400 yards is a deal killer? I don't think so. The main deal killer for me is the energy on target at 400 yards between the above 3 calibers. To me, that's what makes the 7 mag the better elk gun, not the trajectory. At 400 yards, the .308 is putting down 1357 ft lbs. The .257 is at 1064 ft lbs. The 7mm Rem Mag is pushing 1974 ft lbs. I consider 1500 ft lbs quite as low as I wanna go on an elk sized animal. For deer, any of the three, though the .257 is getting pretty weak, still packin' over 1000 ft lbs at that range.
The thing I've found about the .308, though, is that it has plenty of penetration even with that nosler and I have a barnes load for it. It doesn't damage meat up close like the 7 does, and it expands readily. The .257 has never failed me, but doesn't have the meat in the bullet that the .308 does when I see a 250 lb + hog.
I just think .308 is hard to beat by any other caliber based on its case. I have no use for the .260 or .243 or whatever. Just me, though. I'm sure the .260 is quite capable, got great BCs and SDs goin' for it, but I'll keep my .308.