The debate about whether or not the HMR is adequate for coyotes has gone on as long as the round has existed. As is typical in the world of shooters, the it's-not-good crowd is primarily those who don't have one as opposed to those who have taken yotes with one. I have shot none of the critters in question but I opine shot placement makes all the difference and the .17 HMR is accurate enough to allow appropriate shot placement at reasonable distances. I also happen to believe the WSM is a great little round but is trying to fill a niche that didn't exist. Are there still only a very limited number of guns chambered for it?
Believe me, I've tried to talk him into center fire. He has a suppressor for rimfire, and he doesn't want to get one for center fire. He's worried about the neighbors complaining - I tried to explain that he now lives in the country and their whining doesn't matter, but he's not willing to attempt it.
Another thing to consider is the WSM is available with heaver projectiles (20 - 25 grain).