Full disclosure, I tried a head shot one time on a cow elk. 100 yards (I have a hundred yard zero). As stated in some other posts, the millisecond I broke the trigger the cow moved and I hit her bad. I was horrified at the end result and I was extremely lucky to be able to quickly put a follow up shot into her vitals right after. That was the first, and last time I will ever try that. I have shot plenty of animals behind the shoulder and ruined absolutely zero meat doing it, so I choose that route now.
I've said this before, but I think the whole "head shot" debate fall into the category of how you truly feel about your abilities as a shooter, and how realistic the chances of making a clean shot on an animal are. Since I joined this forum, I have actually decreased my definition of my effective range, and I shoot probably ten times more than I did when I joined. After shooting probably close to 5,000 rounds in the last few years in different type of steel matches in different types of terrain, I have witnessed some really odd things happen that could result in a wounded animal. So now, I just try to get to a range where I know my odds of quickly and cleanly killing the animal with minimal meat loss are fully maximized. Everyone has their own view on the subject, this is just my .02.