Heavier Arrow- Quieter Bow.
Heavier Arrow- More KE, packs more of a punch.

I took a random assortment of arrows i have and did a little test over the summer. Probably 6+ different types of arrows, 20+ in all. Different weights, spines, etc. Backed up to 40 yards and with FPs put every arrow in the 4-5" circle ring on my old bag target. Not a single arrow missed this circle, which is much smaller than an animals vitals. 40 yards is my absolute max distance for hunting as of now.