I'll throw my opinion in here... I will be hunting with a guide in the Thorofare in Wyoming.. An area which borders Yellowstone National Park.. If a wounded Elk makes it over that boundary line, you cannot retrieve it..
The guide, who has over 35 years of experience recommends a 7mm Rem Mag as a minimum... If you research this area, its prudent to bring something that shoots flatter and hits a little harder than a .270... He's told me that they have Elk taken every year with a .270, but also they lose well hit Elk which make it over the park border.. Shot placement with any caliber is critical, but why spend that money on a hunt and then take a gun thats marginal at best...
I love my .270, but it will stay home when I go Elk hunting... My .300 Weatherby with a 180 grain partition will do the job far better than my .270.. I know some people can't shot a magnum well, I can...
If you live in flatter country by all means shoot Elk with a .270 with a well constructed bullet... But where I will be hunting its prudent to bring something bigger...
Also, would you rather have to fend off a grizzly bear with a .300 weatherby or with a .270???