This is from the rules of this board.
This board was created for the expressed purpose of discussing the methods, equipment and techniques of Long Range Hunting without the burden of discussing or debating ethics. Although we all individually have ethics and limitations on what we consider correct WE DO NOT discuss nor will we tolerate discussions of ethics on this site. We are here to learn and share methods, techniques and equipment ideas.
So, as far as the ethical part of your questions goes........no response.
As to the part about taking the shot: All variables concerning the animal, weather and environmental conditions and my abilities to make the shot decide whether I take the shot or not. I agree, again, with what Shawn stated, and that is, I take the shot when and if I am of the mindset that I would be amazed if I missed the shot. If that condition and feeling doesn't exist.......I don't take the shot.