Keep in mind PAhunter is talking elk, not deer. That said, plenty of elk have been dropped with archery equipment drawing less than 50 lbs and shooting slower than 150 fps. Like others have pointed out, it is all about shot placement. I admit, I get hung up on the arrow speed myself, but when I do, it is usually because my mind is thinking about the next 3D shoot or next years Pope & young clout and wand competitions. When I get thinking clear about hunting, I grab the heavy arrows. Just flung some freshly fletched douglas fir arrows yesterday evening. They weigh-in around 780 grns. Great weight forward due to 190 grn points. Shot out of a 57 lb longbow. I shot some of my 520 grain arrows (my go to arrows since last fall) before and after shooting the newly made up heavy arrows, and I re-learned why I love heavy arrows....despite the less flat trajectory I was dropping them into the vitals on the foam bear at 35-40 yards, whereas my light arrows were all over the place; over, under, front and back. Fast arrows seem more twitchy to me. Heavy arrows are more forgiving to my release. That and the heavy arrows are always much harder to pull from the target.
I am trained in the sciences too, and I used to put a lot of stock in numbers. Just keep in mind where the numbers are coming from.
I strive to make fast bows, but then shoot heavy arrows from them.