The aileron differential is meant to counter adverse yaw that can occur in some aircraft. For models this is usally long aspect ration gliders or electric assisted gliders. Typically sport power models don't bother with differential. I suppose some of the basic trainer types would fly a bit better with a 60-40 differential ratio but it's not a big deal in my book. Certainly any sort of aerobatic model would use symetrical throws ( no differential).