This is an excellent thread.
I have a feeder mice colony. I enjoy them quite a lot. They aren't nearly as nice as rats, but they are still fun to have around. I try to do everything they need to be happy, healthy, and all that. Every one of them is handled at least a minute or so at least once a week, which has several benefits. First of all, it gives me a chance to evaluate their health a little more thoroughly than just opening the tub and looking at them. Second it tames them down, which makes it easier to do whatever needs to be done with them. Finally, I believe that the more comfortable the mice are with me, the less likely it is that there will be problems with cannibalism of babies.
Many of the mice have names. I am trying to name all of the breeder males, mostly as a way of keeping track of which colony is which. A few females that are more favorites have names also.
However, I was very clear with myself and the other members of the family when we got the mice that every one of them is snake food. The only exception to this rule is if I feel a mouse is not healthy enough to make a good meal. Even the named ones and the favorites get fed off if/when they are no longer a productive member of the colony.
I will admit that the first few times feeding off babies that we had raised up in our house was very hard. The very worst was when one male that was something of a favorite was not getting the job done with his females. So into a snake's tub he went. The snake struck readily enough, killed the mouse, but then turned his nose up at the meal and did not eat it. It made me feel terrible that the mouse had died for no reason.
I do think if/when we start breeding rats, I'll have much more trouble feeding them off, especially the retired breeders. Rats have a lot more personality and form more of a bond with you. So I know after I've had a particular rat around for a while and gotten to know it, that it will be hard to feed it off. I'm not sure what I'll decide... it is a bridge that can be crossed when the time comes.