I think we will try the live first. As for pre-killed, I've never killed a mouse before and I do not know how to do it properly. I wouldn't want the hoppers to suffer because of my inability to kill them in a humane way. (And please do not tell me to just whack them against a wall.)

Thanks for the answers! Hopefully, Sadis and Xefaud will be enjoying a nice plump hopper each, on Saturday.