I'll be the Grinch that stole Christmas for fixed head bowhunters.. Mechanicals win the recovery rate battle.
Will you find your deer after the shot this season? Here's a look at the deer recovery rates when comparing fixed blades vs. mechanicals.
www.bowhunting.com
^^^^^elk and deer is a completely different discussion, so while that is an interesting article, I'm focused on elk, as OP brought up.
It's a tough debate. Agree with most on thread and valid points on both sides.
Placement, placement placement....and shot angle, shot angle, shot angle.....
There are just too many variables where you could make a case for either on certain elk situations. Guys want an arrow set up to blast through shoulder and that is just not realistic IMO....if your going for distance and shoot 290fps with fixed blade to 80yds you are asking for problems. You have to set your own goals and own limits.
For people "harvesting more" with mech, is the blade doing that much better? Would need to know distance. You could argue that forgiveness of arrow flight/tune, is better so guys are shooting more accurately....again just too many variables.
Rib deflection is a real issue, I don't know mech or fixed perform better there.
Total blade cutting surface definitely a factor BUT you need penetration or pass through. Not sure about the "paralell an artery" theory, but I do shoot a 4 blade head.
I have considered having a mech in quiver for a long follow up shot on a bull I've already hit
To OP, experiment, but shoot what you feel you can shoot the most accurately AND have confidence in it.
I'm sticking with 7gr/lb draw wt arrow and fixed blade, 270-280fps