The main thing a more expensive battery charger gives you is the ability to charge the battery more quickly. Some of the stock classes discharge at 40A, then charge at 40A in order to get the internal temperature of the battery higher. This gives the car more punch/speed in the early part of the race. You will need an external resistor bank in order to discharge at 40A. Personally I've never done this. I charge at 12 amps and discharge at 10 amps. 10A is the max discharge my 406duo has without using a resistor bank. I have had cheaper chargers in the past and they would only charge at 6A and it took a long time to recharge after a race. Another thing people will mention is the more expensive models will do a better job of balancing your cells which results in better battery life. Good Luck.