So you did not get the results you thought with your set up or was it because of the angle. I myself would just pass on a bad angle as that makes the shot not a good one to take. I do not remember how far your arrow went in to the buff but you did get it. Not sure 5lbs less draw weight or another 6lbs of draw weight makes the results any better.
Common sense on what shot you take is what archery is all about. The draw weight now a days is one of the least important parts any more in my thinking.
It was an oblique ange and the arrow was mostly buried after impact. It was also close enough that stability may have hindered the penetration.
Passing on shots is something you do when you are smarter. I'm smarter today, then,.... not as much.
One of these days I hope to do another penetration test on a Buffalo. I'll let you know.