You definately need the 1500mah pack. At peak amp draw, your 600mah will not take it. I do not have digital servos on my plane. However, in my heli, I have 3x hitec 6965, one futaba 9254 and a futaba 3001(quite similar to you, 4x digital and 1x normal) and it draws about 200-250mah in a ten minute flight.