The fact remains the most accurate way to compare bullets of different caliber is not weight, it is SD/BC numbers. The better comparison of a 270/150 is not a 308/150, it is a 308/180 (or at the very least a 165).
I've used both the 270 and 308 on everything from coyotes and antelope, through all manner of deer, up to elk. I've used 130's, 140, qnd 150's in the 270, and 150's and 165's in the 308 (though have tested 180's for penetration). What a bullet will do to deer isn't how I judge a bullet... it's just not much of a test. Elk sized game is what I think constitutes a real test for bullets. The 308 Win is my hand's down favorite cartridge (I currently have three), and for elk I mostly load 165's to get just a bit more penetration than comparable 150's. I'm completely aware 150 will work and work well... I just prefer a deeper dig and two holes if I can get them. Pretty simple really...
