The 300 and 7mm magnums aren't going to do anything any better than what the .270WSM already does on animals 500 pounds and smaller.
IMHO you may as well skip over the duplicating cartridges and get into a .338.
BTW, I also agree that the BTSX bullets are way over rated in cartridges that aren't considered to be minimal for the game being hunted. It is my opinion that if you are using something like a .243 to take something as large as an elk then the Barnes bullets are warranted but certainly not with any of the cartridges you mentioned. Dead is dead and just because you spent 3 - 4 times as much for them doesn't make the animal any more dead.