Yes... f/t(Frozen/Thawed)is the safe way to go. First its easy to store the right size food item for your snake. Thawing out is not hard to do. You can buy in bulk. This means you do not have to make the weekly trip to the pet shop. You can even order online and have them delivered to your door.
Feeding live, as the snake gets older, mice can bite your snake. Eye injurys can occur, which I personally have seen happen. It happens so quick that, even if you are watching them, you still can not do anything about it. Feeding live also puts stress on the mouse/rat. How would you feel knowing your getting squeezed to death.
I raise my own mice. It has a plus side, I can pick the perfect size mouse for my snakes. I euthanize my mice and take them directly to be eaten(freshly killed). Before I started doing this frozen mice where by far the superior product for my snakes. If it is eating f/t keep him/her on it. Some snakes never take to f/t and they are at more risk of injury and such.
Choosing between f/t(fresh killed) and live is a no brainer for me. My snakes are my babies and I would hate to see anything bad happen to them. Not that anybody is wrong for feeding live, its just not my choice.