You know, I prekilled almost everything for a long time. One of the things my snakes seem to enjoy the most however is the kill. When I was feeding prekilled they rather lazily took the mouse, might or might not have wrapped it. When I give them live food it's a whole different deal. My snakes become immediately engaged, going into hunt mode. While snakes are not dogs nor do they have the need for "regular cardio". I think it has to be good for them mentally and physically to become their true selves. I've not ever had an injury. This forum and the folks who feed live actually brought me to my decision to do this and I'm glad I did.
Now, if I ever have a mouse / rat cause an injury I may rethink that.