As mentioned by soarrich the CG location has zero to do with the aileron roll sensitivity. If it's too sensitive that is because you're flying it very fast or you have too much aileron still. The CG location will only have some influence on the elevator response.

Having flown a few small fast models I found that at high speeds it takes very little control deflection on any surface to get a strong reaction. But you still want enough for when gliding in slowly to retain a reasonably strong control response. The solution is to either use dual rates to set the controls up for the two extremes or to just get used to barely breathing on the sticks at high speed.