Spades only work if the ailerons are inter-connected, like they'd be on a full-size aircraft. Their purpose is to lower stick forces. If you're using separate servos to drive your ailerons, then the only purpose spades would have is for scale effect. They would not add anything aerodynamically to the model, except as counterweights. Then, you'd have to make them well out-of-scale to get enough weight to be effective...may as well use a streamlined weight.