On some corners aw drifts are undoubtedly somewhat faster, that includes some sweepers contrary to what you said (or so I think anyways...) When I ran my Laguna Seca times I did both grip and drift, and eventually I found what I believe to be a fairly close to perfect lap. As I said, I do both now.
Even with Super Softs you can get more angle than any FR, that's the whole advantage of AWD drifting--they can go more over and still recover, which accounts for their high speed sweeper ability that RWD doesn't have down pact quite as well. Even so, when trying to mix it up, the GT-R isn't as great as say the Lotus Esprit or Viper GTS (which I consider to be a crappy car btw), which both dominated my GT-R times with ease, also using both styles.
The AWD cars that certainly have my respect are the GSR and TME Lanevos, only because of the AYC. Even then, those cars don't have the kind of torque on demand I like. Maybe I said all that wrong, see, I still like the GT-R, and many other AWDs like S4, VR-4, etc., but I'm taking a break from them all for now.
I was just sayin it's my opinion that RWD is t3h best.