Ah yes, the Chrony strikes again! "The truth shall set you free."
The difference in MV and trajectory between 280 Rem. and 7mm Mag., 30-06 and 300 Win. Mag., etc. is real and always in favor of the magnum on paper. BUT...when you factor in the many variables connected with a specific rifle-, ammo-, and shooter-combination the PRACTICAL difference in the field pales to insignificance in most (not all) cases.
I have to admit that my accuracy is inversely proportional to the power of the cartridge. I shoot my .223 and 257 Roberts better than my 6.5X55, the 6.5X55 better than the .280 Mtn. Rifle or the 30-06, and all of them a little better than the 35 Whelen. I'm a fair shot with the Whelen, my favorite for elk, but I shoot better and better as I go down the power ladder.
In my case, giving up a few hundred fps, and the perceived recoil that goes with it, is more than a fair trade in field performance.