my experience tells something else, I never even noticed Riegler drove with mouse. He's one hell of a good driver tough and very consistent. Never had trouble with him in close battles.
maybe impossible for you, since you don't use mouse. People who use mouse for a long time can keep it consistent and stable. Even tough they do have it way harder under braking, when racing with other cars they are still just as safe as wheel users. it's all about how long and how much you use it