Not sure exactly why this issue keeps coming up. As for myself, however, I will say that I have always been concerned about ethical shots.
Last year, I went crazy trying to find my perfect setup to hunt Africa. My setup was almost identical to yours. And I was able to come home with a Wildebeest, roughly the same size as an Elk.
My research showed that all issues were marginal. Heavier arrow had only marginal increased penetration. Lighter arrow had only marginally less drop at 25 yards. So, in the end, I built the arrow I liked. BTW, I used a 150 grain, 2 blade stinger with some other weight attached to the insert inside.
Bottom line, you'll be fine with what you have. Practice, practice, practice... Hit what you're aiming at, and have sharp broadheads.