Live rodents fed to snakes get extremely stressed and produce a hormone called cortisol which does not get digested by herps, in fact it can enter the bloodstream much like estrogen does in mammals and contribute to stress-related diseases.
I see absolutely no reason for not stunning or preferably killing the prey first. It's far healthier for the snake. No matter how big a cage we provide our snakes do not get the exercise that a wild snake does and can't work off the "fight or flight" hormones effectively. So they are prone to develop immune system deficiencies, liver disease and obesity caused by high cortisol levels.
The Zombie Mama is here!