I have both , two 17 HMR'S and the 22 Magnum. I have killed maybe ten or more coons with the 17 HMR and they died right there. The 17 is a much better killer if you use the 20 gr XTP and stay away from the 17 gr Vmax even tho i have killed a few groundhogs with the 17 gr and they died instantly. The 22 mag is my choice when you get to animal bigger than coons and foxes . Most people who put down the 17 HMR have never used it or shot anything with it. Accuracy wise the 17 HMR has it all over the 22 mag when you get pasted 50 yards. In my opinion no rim fire is a coyote killer unless it is the only rifle you have, then call them in close and make no bad hits are you will cripple but that happens with center fire also. The 17 HMR is the best round i have ever used for gray and fox squirrels and this is where they really shine. If the 17 Hornady is the only rifle you own then hunt with it but use the 20 gr XTP, if you own something bigger then use it for coyotes.
