My oppinion is that there is no super cartridge that breaks the rules of physics, and does things exceptionally better than all the other cartridges. There are those out there that think that specific bullet diameters are somehow magical, and pixies guide them through the air both straighter and flatter; if anyone believes that, I have a few bridges for sale.
What matters for trajectory is initial launch speed, and the bullets ballistic coefficiant. Drop a bullet on the floor, and you will see how fast that bullet actually drops (hint: they all drop the same speed). The faster that you push a bullet forward, the further forward it will go before it hits the ground. let's put this in perspective. All things being equal 100fps more will allow the bullet to travel approximately another 1/4" before it hits.
When the bullet leaves the bore, it is immediately slammed into a wall of air. The more streamlined the bullet is, the more it will be able to overcome the air resistance. To put this in perspective, a .308dia spitzer boat tail with a ballistic coefficient of .452 started at 3000fps will be travelling 2790fps at the 100 yard mark. a .308dia 180gr round nose with a ballistic coefficient of .241 started at 3000fps will be going 2614 at 100 yards. That puts the BT spitzer down 3" at 200 yards, and the RN down 3.6". Does this sound like much?
To further complicate things, when a bullet is launched faster, the initial air resistance that it meets is increased rather expedentially.
This rather long winded post is simply attempting to show that people tend to make mountians out of molehills. Will the 270winchester shoot flatter with a 130gr bullet than a 308win with a 150gr bullet, sure it will. Will you notice the difference at normal hunting ranges; probably not. A .277dia bullet travelling at 300fps with a 100 yard zero drops 11.4" at 300 yards. A 150gr .308dia bullet, started at 2800fps with a 100 yard zero drops 14.6". There will be holdover needed with both in that circumstance., and one is only 3.2" better than the other.
Mike