Shooting flat is only an advantage when you're looking at using a point blank zero or shooting at an unknown range (no LRF). If you are shooting at longer ranges and dialing your elevation and know the range. Being flat shooting is of no real advantage. Drop is very predictable. Using only the above examples, the .270 is the superior choice because of the higher velocity and BC. Not because of energy but because of wind drift. At longer, known ranges, a competent shooter will not miss high or low because the bullet didn't drop as expected, they will miss left or right because they misread the wind. A higher BC and/or higher velocity reduce the effect of wind as a whole and thus reduce the effects of a misread.A 130 gr. BT hand loaded will easily produce 3150 fps M.V. with the .270 win. The .308 doesn't have as flat a trajectory shooting it's best performing bullet. A 150 gr BT .308 bullet with a BC of .42 zeroed in at 300 yds. drops about 32" @ 500 yds. with a MV of 2900 fps. A 130 gr. BT .277" bullet with a BC of .46 zeroed in at 300 yds. drops around 25" @ 500 yds. with a MV of 3150 fps. Both of those estimates are based on a realistic obtainable velocity with reloaded ammunition, not factory. Factory will not likely produce as high muzzle velocity for either cartridge.
The .308 is a marginal competition cartridge at best. Pretty much the only people that shoot .308 in comps are those that have to because of the particular discipline that they're shooting, like F-TR. For those people it isn't a handicap because their competition is shooting the same thing, leveling the playing field. For competitors that have a choice, a different cartridge is the choice. The .270 COULD be a good competition cartridge except for the lack of efficient bullets. 6.5mm is the passing fad, but 7mm is the real deal and more competitors are going that way all the time.There are other bullets that will increase the BC by quite a bit. But BC isn't going to do anything for much needed velocity for a hunting application. I know I'll get hammered by the many .308 fans out there, but the simple fact is what may produce an excellent competition cartridge, doesn't always make a good hunting cartridge. Those who shoot 1000 yd. competition are not likely to pick the .270 win..