Yes I would stick with one of the tried and true. 270, 30-06 308 7MM Mag or 300 Mag.
I don't know how many elk I have killed in my 56 years of hunting them, but I have owned and used several of the new hot fast super mags. And you are correct. Out to about 500 yards I can see no real difference is the quickness of their deaths between a 270 and a 7MM STW or a 300 Weatherby.
What I can and have seen is the difference between bullets that break apart badly and those the hold together well.
Not to mention recoil, and who can handle it for good bullet placement. Which is the be all and end all. Better a lighter caliber with good bullets than an eye-ball rolling flincher magnumamus. (I have a .338 Wm, I can shoot fine, in the field, but 5 rounds at the bench is all I can take - It's served me well for 25 years or so). I don't flinch with the .338, but I love my .260....
Premiums are fine if they float your boat, but most modern C&C are all I use anymore on either caribou or moose, which kinda bracket elk. I won't use Fed Hi-shoks on game, however, from experience.
