This. I simply won't do it because the margin of error is just so small, and the head of a feeding deer moves more than anything. Slight movements mean BAD misses if all you're aiming for is the brain.

I've seen trail cam pics of emaciated does who are starving to death with a bottom jaw hanging off due to attempted head shots that went wrong. It's cruel.

It's all cool and stuff to brag about, but it's a matter of when, not if, you booger one up that way.

Personally, it's not worth it to me, but everyone's conscience is different.