I disagree with the statement that "head or neck shots are the only sure shots" to kill a deer head on. There is no such thing as a "sure shot". When someone start think there is, they can get careless or quick to snap off a shot that wounds but may not kill the animal. A deer hit slightly off center on a head on shot may be wounded and run for miles.

Unless you have a great solid rest and the animal is stopped taking a shot like that is a risk, in my opinion. I'd sooner wait for the deer to turn to get a through the lungs/heart shot that will bring it down in less than 100 yards than to risk wounding it and trail it forever and maybe never catch up to it.

That's just my opinion.