I have heard of the ferret thing. The difference here I would say is that the food item is the same -> if they imprint on a rat they're still getting a rat.
AK - I hear people say that in these threads. I haven't seen a single person confirm your claim (beyond very small hatchling snakes). The closest I've heard is what Slim just described which, while inhumane from a domestic pet standpoint, is sustaining the snake's life. My pewter was 150g and a year old when I bought it and it has no permanent effects and is now gaining weight rapidly.
They have the know-how to sustain life. They have genetics telling them to eat food BY OPPORTUNISTIC MEANS that is millions and millions of years old. They eat dead things in the wild if they need to. In captivity, we simply measure NEED differently. I don't disagree with that notion.
If I ever get a multiple refusal snake I will most definitely feed it live. Here's the thing, though. My 4 snakes are all on F/T now and haven't skipped a meal. If at some point they choose to do that, I'm going to wait until they take F/T again to feed them. Why? They know it's food and they know what to do. They're not THAT stupid.