A Porsche 911 handles different from a Ferrari, but that doesn't mean one has a design problem over the other.
Having many hours of street and track time in a wide variety of Porsches from 356s to a 917, being a committed Porschephile, and having written a book about one Porsche ("The Gold-Plated Porsche"), I can assure you that the 911--and the 356 before it--most definitely has a design problem. Even Porsche AG will admit it, and point out that for half a century they have been trying--very successfully--to overcome it.
Putting the engine behind the rear axle was a reasonable idea for the original 36-hp Volkswagen, but it's a dumb way to configure a car with anywhere from 250 to 750+ hp.
It's why Porsche doesn't dare put a truly powerful 911 engine in the mid-engined Boxster. That would make the Boxster such a fabulous car that it would be difficult to continue selling intrinsically flawed 911s.