17 mach 2 is the funnest round ever made, for ever, I love it, but i do have both.
the hmr , i would not hesitate to take a coyote with it, the mach 2, I would but it would have to be close, like sneak up on me close, even though it may not be necessary.
the mach 2 will also shoot the 17pmc / 17 aguila round. I love the 17 aggies, it is a 20 grain fmj round, that zips right through your game, without blowing it up. the 17hmr will blow up small game, all the way up to fox size really.
anything smaller than a fox, you may or may not have much left.
ammo is much cheaper in mach 2 form, especially if ordering off the internet.
you can find it for 4 to 5 bucks a box, easy, from many diff sites. ammotogo, still has some of their Eley mach 2 for 3.50 a box, which is totally sick!!!!
Here are some places to check out trajectory, energy, etc.
http://www.varminter.com/
http://www.varmintal.com/17hmr.htm
http://www.chuckhawks.com/index2l_rimfire.htm