Sure. Mid-engine alone isn't enough to trump all other
differences, certainly, but fundamentally if all other things
are equal, mid-engine is superior to rear-engine, and
Porsche *could* make all other things equal between the
GT2 and Cayman if they wanted to.
The two things I think Ferrari are superior at are visual
design, and getting a lot out of normally aspirated engines.
If they had the same long-term reliability and maintenance
costs as Porsche, and the same real power under the curve,
by having as good and strong a motor as the Porsche 3.6
turbo, they could become a superior car on the track.