Nutritionaly I would summize that gerbils are better than mice, and about the same as rats.
Yes but nutritional requirement of Ball Pythons are not know so gram per gram of prey it is all the same.

As your BP gets bigger you may have to feed multiples to get close to 10%-15% of it's weight.
Are you saying a 3000 grams females needs a 300 to 450 grams rat?

Do you realize that this is way much more food that they would ever get in the wild, that an overfed BP will fast to catch up and that feeding a 300+ grams could very well put your BP at risk.

BP do not need large meals to thrives one small rat (4 weeks old) weekly is enough even for a large adult, this reduces the risks when feeding live and also allow you to have BP that eat with consistency.