Yeah, that's pretty neat how protective she is (or aggressive, depending on your point of view
). Either way, it sure seems like it would be handy to have a mule like that on a cow calf outfit.
I met a guy that would only work calves (when dragging them to the fire) with one particular mule. I saw them working and can't say I blame him; that mule did everything except throw, dally, and coil the rope afterwards. This guy could drop the reins and the mule would set up the shot, turn around when the guy got dallied up, and would walk right over to the ground crew. It was pretty cool to watch.
I agree with you about using a mule for heeling; the right one would probably be tough to beat. I'm sure someone does it competitively, I just have never met anyone that does. I really like watching a good mule work.