It proves that the 260 Remington with a 140gr bullet matches a 300 Win Mag with a 190gr in trajectory and wind drift out to 1000 yards. This has been mentioned and explained a few times in this thread already.
Sure we could compare the 260 to the 264 Win Mag if you'd like. Any time you push the same bullet faster, you'll make it shoot flatter and drift less in the wind. This higher velocity comes at the expense of more recoil, longer & heavier rifles (all things equal), shorter barrel life and less accuracy. There's a reason why long range competition shooters choose the 260 Remington or 6.5 Creedmoor or 6.5x55 or 6.5-284 Win over the 264 Win Mag or 6.5 STW
Nosler manual shows the highest velocity load with the 264 Win Mag & 130gr Accubond to be 3166 fps with RL22. For the 260 Remington, 2911 fps with AA3100. That 250 fps advantage would yield 3.5" less drop than a 260 @ 400 yards when both cartridges are zero'd @ 200 yards.
I don't know about you, but my crosshairs probably wiggle 3.5" at 400 yards from a steady field position. I probably couldn't take advantage of that extra velocity
What I can take advantage of is the lightweight compact rifles the 260 is often chambered in, which come to the shoulder quickly for those common hunting shots in the 50-200 yard range