Every snake that's been brought into my collection is offered live, even if they've been life long f/t feeders. In my own sampling of over 3000 live prey fed off, I've never had an injury to any of my snakes, including those who have been raised their entire lives on f/t. I've said it before, even if I'd had just ONE injury, that risk calculates to .0003% chance of injury from live, un-stunned prey being fed off.Anyway... I completly agree that your method should be safe... For a snake USED to feeding Live. I recommend stunning in the beggining simply as a safety precaution for what might happen. Better safe than sorry, and once something happens it is already too late. There will ALWAYS be a risk while feeding live aware prey... The same danger exists in the wild.
I hear the arguments of the danger of offering, as you put it "live aware prey" from many people - but my own experiences just don't validate the risk.
I also am not feeding medium and large adult rats to my snakes either - they are getting no larger than a small/small live rat. If they are exceptionally big girls, they may get two small/small live rats. The rats have no clue that the snake poses any danger to them until it's too late. They're usually quite content to sit in a corner and groom themselves or explore the enclosure if I have a snake that's just not interested that week.
To sum it up - in my personal experience I have not experienced any difference in the level of killing prowess from a lifelong f/t feeder offered their first live prey, or those who have been lifelong live feeders.
With that said - I'm not encouraging anyone to feed live over f/t, nor am I encouraging anyone to feed f/t over live. I think either works just as well for what the keeper is most comfortable with. What I am trying to discourage is the over-dramatized "danger" of feeding live, when if done as outlined above is a negligable risk.