I feed mainly frozen thawed but my babies get live rat fuzzies and rat pups. I used to feed mainly live but after having a couple rats scratch up and bite a few of my snakes, anything larger than a rat pup is fed f/t. I have not had a problem switching any of my snakes over yet. I give them an extra feeding cycle so they are hungry and they usually take it without a problem.
I try not to feed mice to my snakes, but sometimes I have to substitute a hopper or two for rat pups. The rats seem to help the snakes grow faster and for a while I had some snakes that were on hoppers and some on rat pups. The ones feeding the rat pups seemed to have a better muscle mass than the ones on mice.
I really have no problem with the snakes killing the rats, I just want my snakes to be safer. It may be natural for them to feed on live, but it is nothing I want to chance any more.