All I know is that after shooting coyotes with a 243 & 55 grain ballistic tips going around 4000 fps, my results have been anchored, or dead coyote. After watching many, many getting a good hit with a 223, they still can travel a bit. As long as there is a good amount hydrostatic effect, the vote is down. After having several not die instantly with a 88 varmint bullet, after good hits, I think all of it matters. Speed, design, and placement. I have had knock-down hits on coyotes with a 270, and then have them run like they weren't even hit. 110 Vmaxes, 130 VLD's.
For coyotes and at distance, I'll keep using a 6mm of some type.