I feed live and f/t to my snakes. I've been keeping snakes now for 5 years. I keep over 30 snakes right now and have plans to expand my collection.
Firstly, I feed the majority of my snakes f/t. This is out of convienence only. I would much prefer to feed live, but if I were to feed live I would want to breed my own (because the sources of live rodents around are not that great...parasites...ill rodents...malnourished) and I simply do not have the room to do so. Many of my snakes have no problem switching from live to f/t from one feeding to the next. They simply do not care. However, I do have a few snakes that simply refuse f/t. They will starve themselves for months until they get a live prey item. Of course, I have no problem feeding live, so this is not a problem for me.
When I feed live, I am very careful with each feeding. I supervise each and every live feeding, tongs in hand, ready to intervene should the snake strike wrong. If the snake does not strike within a few minutes, I pull the rodent and leave the snake for the next feeding day.
In my 5 years of keeping snakes I have only one snake that has ever become injured. It was a very small bite wound on my snow corn snake from a live mouse. Within a few sheds you wouldn't even know she'd ever been bitten and it certainly has not scared her into not eating. She's an eating machine and will take down any prey item you offer, live or dead.
Also, I NEVER stun a rodent. I find this to be a cruel practice. It can also be dangerous to your snake. If you stun a prey item and it ends up coming to while in a tub with your snake, the prey item will more than likely be very frightened and more aggressive. You would be too if someone knocked you senseless. I used to stun mice for my snakes when they were babies. That was no problem. The first time I ever tried to stun a rat, I almost cried. The poor thing went into seizures. I will never again stun an animal. Either kill it and offer it p/k, buy f/t, or feed live. There is NO reason you should have to stun a prey item.