RE: .204 Ruger vs. .22-250 Rem.? or maybe?
A 40 grain .204 or 55 grain .243 both provide better ballistics than any .22 caliber in factory ammo selection. I don't know about pelt damage though...
Didn't you just get a Weatherby .243? I'd use it with the same loads you decide on for pronghorn and it should work great on coyotes, plus provide you with a way to get even more familiar with it. If you're dead set on getting a new gun, look hard at a cz 527 varmint in .204. They have nice little slick actions, nice balance, a medium heavy barrel, and yet they aren't really heavy. I would love to own one if it were financially feasible.