I think it would definitely help sandbox gameplay if I could alter the talkativity of the undead. Playing on sprinters without being able to hear them is pretty jacked-up. In most sprinter-zombie lore, they tend to jabber and shout, none of this grunting and hissing you slower folks practice. A couple of degrees to this would certainly be ideal, too; players could then set stealthy, slow zombies who rarely attract the attention of their friends or the survivors, obnoxious, horde-prone sprinters, or moderately loud, moderately fast shamblers who group up like normal. Or something else, I don't know.