I would take the shot. 6" window at 15yds. is looking pretty big. I will differ from most here though. I am not knocking a quartering away shot, it is a good one. But, I greatly prefer a nice broadside shot over any other. Heart shots are nice, heart/one lung is nice, but time in, time out, a good broadside where you centerpunch both lungs, and pass through the animal quickly, will result in a faster kill, with shorter trail. I base this on a ton of my own experience. I`m not that young, and have been foolish enough to spend most of the money I have made in my life, hunting whitetails in every state I can get to. So, I`m talking alot of bowkills here.