Rabernet has posted before that out of 15K or more feedings shes only had maybe 5 serious bites that needed some sort of treatment. Thats a .9996% success rate, if you don't wanna round it up to 100%. Thats close enough for me. (I'm quoting from memory so I apologize if that stat isn't exact).
These guys are designed to kill, and they do it very well. Even if they don't get a good hit and your snake gets nipped by the rat or scratched (in other words a non-serious injury to their body) who cares? It'll heal in a few sheds. I keep my tubs clean so its not like theres a very good chance its gunna get infected. I mean, I try to avoid it, but if it happens its really not as big of a deal as people make it seem imo. You've never burned your mouth on a piece or pizza or a cup of coffee? Or bit down on a chip wrong and have it stab into your gums? It doesn't mean i should have someone pre-chew my food for me or serve me luke warm coffee.
EDIT: I'm not saying you should feed live, just making the point that it's more than safe to do so.