I don't know about the bus ,but Boeing recommends usage of center tank fuel first,for structural reasons. The 2300 kgs restriction on the Ng is temporrary,untill all pumps are checked,and it was calculated for take-off as the minimum fuel quantity in center tank ,that won't allow the pumps to uncover in any pitch or acceleration achieved during take-off.
After constant climb is achieved,the center tank pumps can be scwitched on again.
Why would you want to take-off with center tank pumps off if above 2300 kgs?
there are differences between A and B,so don't try to operate one as the other.Different wings,fuselage,systems,etc...