With my aggressive feeders, it doesn't matter where I feed them, they are always going to be cage aggressive. Even if they aren't used to being fed in the cage, if they see a warm, moving, pulsing thing (my hand), they're going to try to eat it. Then of course picky eaters are less likely to eat in a separate container. And why even try? Picky eaters aren't going to be cage aggressive.

In short? Feeding in a separate container is pointless. But if you want to, go ahead.