There is no way understeer is faster than oversteer. You obviously can't drive RWD. If you giving loads of lock, then yeah. But if you catching a whiff of oversteer & are keeping the throttle & momentum going forward you will gave good exit speed. With understeer you have no option but to lift to get the nose in & then re-apply throttle. With oversteer you can keep the throttle buried & steer with it while getting the nose to the apex & powering out.
But I agree the R8 is the best handler out there at the moment. The videos I have seen have it oversteering while nicely, especially when Tiff drove it. I hear it can send up to 95% to the rear which is probably why it handles so well.
Use to rally the Mk2 Escort so probably you are correct, I know nothing.