Wow! Thanks for the comprehensive overview , but this is going slightly off-topic, so I will attempt to bring us back.
The reason I wanted to know this was to find out about performance of the mini 9398 with a standard AA battery box, but I just realised that it was mentioned earlier as poor. What do people think is the best approach to a rock crawler; minimalistic, with low power and low weight, or heavier, with a high power drive of several large or XL motors?