If you take the same car and could switch it between RWD and AWD then I don't think there is much effect on cornering speed when you keep a constant pace through a corner. The grip is purely dependent on things like down-force, tire contact area and suspension keeping the wheel on the track. The handling changes a bit when you are speeding up or slowing down around a corner though. The RWD sacrifices some of its rear wheel cornering grip (in the direction of the rear axle) for acceleration or deceleration grip (in the direction the car is pointing) so the rear of a RWD will slide more than a AWD car which spreads that effect to the front wheels as well. This could actually be better for the RWD cornering but you would really change the setup for AWD to try and get the rear to slide more. I'm no racing physics expert but I think you should consider the advantage of the AWD to be in the traction zones on the exit of slow corners rather than giving any advantage in the middle or exit of a long fast corner like 100R.