RE: less power from 400 motor, 30 esc, 10 cell combo
fwiw as a point of comparison, I am using 10 cell KAN950 pack on a S400 Long Can and 5.5x4.5 APC prop - it pulls +15A and pack voltage is just shy of 10V. As David mentioned, there are couple of difference 1100 2/3A (I presume that's the size you have) out there, the generic ones (BatterySpace/BYD) won't give you any performance at high current drain - stick with known cells like KAN and CBP's if going for 2/3A's (imo HECells have been left behind).