Maybe I am missing your point, but for any of these calibers, you can adjust the bullet at 100 yards to get the most out of trajectory, so I don't see where the trajectory is a major problem for any caliber even using bigger bullets. So even if trajectory is a wash, the energy of these calibers is certainly not a wash out at 300 yards. However, you can't use light bullets in the larger calibers. For example, here are the ft/lbs of energy of each caliber with what I consider more appropriate bullets:
270 130 gr 1700 ft/lbs
30-06 150 gr 1700 ft/lbs
300 win mag 165gr 2100 ft/lbs
300 ultra 180 gr 2600 ft/lbs
338 win mag 225 gr 2700 ft/lbs
So, as far as energy, I certainly wouldn't call them a wash. All of those bullets can be adjusted trajectory wise for a dead on hold on out to at least 250-300 yards
And if you really want to drive yourself crazy check out the Taylor index which gives bigger bores the nod for knock down power:
http://www.loadammo.com/Topics/July02.htm