If a person is currently feeding in a seperate tub and having success at it, I don't feel any need to argue differently. LOL
That being said, I'll tell you why I prefer to feed in their own enclosures...
One: Some snakes are extremely shy eaters and the process of moving them into an unfamiliar tub can quite easily put them off feed. (My gopher snake falls into this category for sure!)
Two: It significantly reduces the chance of accidently causing your snake to regurge its dinner due to the handling required to move it from the feeding tub back into its own tank.
Three: It's just simpler for me personally, and anything that doesn't hurt them while makes things easier for me is a "plus" in my book.
Four: I have no idea if it means anything to the snake or not, but I get the feeling that it could be stimulating (in a good way, rather than stress inducing) for them to actually get to "hunt" for their food. Even if you feed pk or f/t...they have to come out of their hides and find it. That is pure speculation on my part.