It all depends on the snake. I have some snakes that would rather eat in the cage and some that like to be put in the feeding boxes cuz then they know its time to eat. It all depends on what you teach your snake to get use to, and reading your python. If it seems to eats better, or seems to like one way or the other better, do it that way. Some of the "cage agressive" things you hear about depends on the time of year also. Right now almost every single one of my snakes is very agressive and sometimes even strike the side of the tub if I walk to close by. Lol, not that I mind them eating alot though!!
Anyways, just pointing out there is other ways to do it. Like the rest of your pointers though!