I feed in the tub, and always have. I've never had an issue with cage aggression.
New owners think they need to feed in a separate tub so the snake doesn't start to associate their hand with feeding time. For some reason, the fear of getting bitten makes new owners think this is a logical thing to do. Here's my break down of that thought process:
1) You stick your hand in the enclosure to handle the snake for husbandry and such, right?...you stick your hand in the enclosure to move the snake to a feeding tub, right? How is the snake ever supposed to know the difference? If the snake is going to make associations, wouldn't it be with being picked up? Things that make you go hmmm...
2) Let's say you move your snake to a feeding tub and successfully feed him. Now you have to move a snake that's in feeding mode back to its regular enclosure. Tell me again how you don't want to have a snake associate your hand with feeding time
3) If you use long tongs or hemostats to introduce the prey (which is recommended) how can they associate food with your hand?
4) The two things that trigger the feeding response are scent and heat. So, don't smell like a rat, and you won't trigger a feeding strike.