dont know if this helps, but look at it like this: the prey items are going to be eaten by another snake/animal if not yours. they were bred for that. i would try with f/t. there are plenty of instructions online/youtube on how to make the switch, just in case he was eating only live. I feel that the previous owner did a pet shop technique, where you were told that Spencer was eating both live and f/t just so you would see no problem with feeding. "oh I can feed it live if i want. cool." or "oh sweet! i dont have to feed live!" thats how i feel anyway.