I tried this a long time ago on an aerobatic plane. It seems like you need to get that gyro right on your CG inorder to crank up the gain. It works if its within 10-15 cm but it caused me to have a false sense of control.. If you are trying to make and unstable plane like a jet be stable, then this is good. If you are trying to make an aerobatic airplane more aerobatic, you are cheating..
Century Helicopter products used to sell some micro 3 gram gyros that worked pretty well..might want to try those out.