I prefer F/T for "humane" reasons, since CO2 or pithing is a less painful and terrifying way for the rodents to go then being bitten/constricted. I've owned both (rats/mice & snakes), I completely understand why its hard for some to be there for the actual process of watching their snake kill a rodent. There's absolutely nothing wrong with that, as long as it's not putting the snake in a position to be injured by the prey item.
That said, I came into mine knowing he had a bad feeding response/regimen, and knew having to feed live might prove to be something I'd need to consider. Knock on wood, I haven't had to yet. Hope that continues, but will cope if it doesn't.