I fully expect to use 5th. I hit the rev limiter at MAM if there's much of a south wind. And the front straight on that is probably about half a mile.
I'm going as a student, and will use the Subaru with street tires until I feel comfortable enough to take the fast car out. And since it's an Audi club, I'm sure I'll get an instructor who's familiar with AWD. They're quite different.