RE: anybody had experience with these "varmint" rounds?
Sierra makes a 90 gr. HP for the .270 that I have used with very good results. Edward A.Matunas made mention of the amazing accuracy potential of this bullet in an article I read in the late 70's, using a load of IMR 4350 a couple grains below maximum. Very similar in performance and recoil to a .243. A friend of mine has also used 100 gr. factory .270 Winchester loads with pretty fair results.
Bad news is that both of these bullets are hard on coyote pelts. I think you would be better off using a Barnes X bullet - really doesn't matter what weight, whichever one your gun shoots best. Unless you hit big bone, these will usually whistle right through a coyote and leave an exit hole about the size of your little finger.