I believe that if the car is correctly setup I don't need it, am I correct.
My experience is that I have a gyro for my Mini-Z, but after after I fixed the problem on the chassis (there were some imbalance and tweak) the car is very stable and don't need a gyro
but same people said that set the car to be very very responsive in turning, and then use the gyro to make it drive-able. Then the car will have good turn and also stable on straight.