I had a p-o'd dominant male jump over me from behind on the way to an electronic call once, and had another spray rocks on me as he turned to go, but have never been "attacked" or heard of anyone else being attacked either. I just don't see any coyote without rabies attacking a grown human, and I don't give it a second thought.
On the other hand, calling in cougar country tends to keep me backed up to a big tree or a rock.