Living in Colorado, I see plenty of guys (including buddies of mine) lugging plenty of big bore rifles into the woods.
Funny thing is, they all practice year round and shoot deer and antelope with their .270's and 30-06's, then when elk season rolls around they grab their.338 or 7 MM's. They don't know how the gun shoots, and they don't have time behind the trigger.
Anything .270 andup will kill an elk DEAD. If you own a .270, 30-06,or some other applicable rifle that you use frequently and are comfortable with, take the money that you would have spent and buy a plane ticket, get out here, and SCOUT. That will do you more good than 1 inch less drop at 400 yards.
In my opinion, you're better off with a slightly lighter caliber that you KNOW inside and out versus some magnum cannon that you don't have the experience with.
(edit: Notice that I live in Colorado and big game hunt,and my .270 is my go to gun!)