Actually, there have been several deaths associated with taser-use - though nothing conclusive has really been concluded (i.e. the taser ALONE caused this death). One can read about such things here:
Either way, one should want something to tactically exist between a compliant arrest, and punching somone in the back of the head and/or using a taser on a suspect. With such options, one's escalation rate is greatly decreased - just like in these forums when a person has some emotional and/or verbal skills, they aren't so prone to fly off the handle as if their village is being burned by the person that says something to the contrary. It's options and maturity that make a person a professional. Anything short of that has a person floating somewhere between lucky and that one case where one's lack of professionalism is exposed for what it is (i.e. not knowing what to do and thus having a capacity to over-react). It's really the same for all of us, no matter what field we are in, and no matter what situation we may be in. Isn't it?