I've always fed live, I've never fed pre-killed or f/t. I have 17 ball pythons. None get larger than a 4-6 week old rat (the equivalent of 2 adult mice). I've never had a bite or scratch on any of my snakes in over 2000 live prey being fed off.

I do not encourage switching to live just for the thrill of watching your snake dominate a prey item. It's up to each individual keeper to decide what's most convenient for them.