I was thinking of much more closed courses than Silverstone. Example: ever notice how one autox course can differ so dramatically from another even though they all cover roughly the same area in layout? I've become reasonably good at guessing who's laid out a course over time. If, say, the course is a broom closet with one S after another and more cones than an ice cream store, it's the Miata guy that designed it. If it's the Bonneville Salt Flats, it's the Corvette guy that designed it. They tend to lay out courses to their strengths etc.
To the OP's subject, and ignoring straights (they are in my view not meaningful):
I'd rather drive the WRX because I find it easier to drive. I prefer understeer and the extra displacement could forgive a mistimed shift or an earlier lift at the entry by letting me get out of a bend a little better -- at least that's my hope. It is my impression that a novice would have an easier time moving a WRX quickly than an Evo.
I do believe the Evo is a quicker car, but the WRX is a better car. I'd buy the latter but borrow the former.