This is going to turn out to be a huge debate. I personally feed inside their enclosures. I think whether or not someone moves to feed depends on the snake itself. I have one or two that would probably do fine if I took them out to feed them, and a few that would go off feed indefinitely if I moved them to feed. I think it all depends on their personality and sense of security. I have nothing against people who do move to feed, if it works for their bps then great, but if someone continues to move to feed then complains that their snakes hasn't taken a meal in 2 months...that could very well be the problem.
I feed all of mine, including my boa with a very strong and quick eating response, inside their enclosures and I've seen no signs whatsoever of "cage aggression". I can reach into at any speed into any of their tubs and will not get bit and mistaken for food (unless I smell like rat....obviously you have to be smart about it lol).