i vote for wheelspeed too! its more realist to me and it gives better indication of how much you are wheelspinning!
could have an option to use either real speed or wheels speed i guess for people that likes it the "old" way (if its ever implemented)
its not the sensitivity of the foot, its the brain that cant give a precise movement to the foot, im sure your left hand is has sensitive as your right hand, now try writing something with a pen with your other hand...