When my daughter and I got our first snake we fed live rat pups. As they grew and their prey got bigger I started getting nervous about the teeth. When Rex insisted I take him home with me I fed him live as well - it was the way we were told to feed by the shop owners. We didn't know any different. I always felt a bit of success when they struck and killed their prey at the same time feeling a bit sorry for the rat(s) and their apparent suffering. Then I found this place and started questioning the method of feeding. And I finally 'met' Chance and Louise.
I was appalled at the injuries and greatly admired how Louise took care of Chance. So thinking I was doing a good thing I started feeding f/k and it went well . . . no problems switching at all. Then one day a medium rat 'woke up' from what I thought had killed it. That rat was so mad and I was so scared for Rex - I was a nervous wreck that feeding. After that I made good and well sure that the rat was dead, dead, dead.
Having heard how hard it is supposed to be to switch BPs to f/t I was unsure about it. Finally took the plunge and only had to wriggle a little bit the first couple times. Rex has always been fed outside of his enclosure - and has to date never refused a f/t feeding. He may play with his food for a while - but does eat it. And now there are times he doesn't even strike . . . just plays and starts to swallow when it suits him.

I now have confidence that he will never get bitten, should not get any parasites from his prey, and that switching can be done. As I was once told - it was me with the issues and not my snake.
I totally agree it is proper thing to do to feed f/t. That being said - I hope that when I get my baby snakes there will be no problems using f/t over live pups. But if I have to use live - at least there are no teeth to injure them and they will be eating f/t long before that would be a concern to them or to me.