1) The Lambo and the Porsche are 4x4/AWD but the Lambo doesn't come with stability management systems.
Sorry what? You think the Lambo doesn't have traction control? This isn't a TVR, there is a computer helping you. The Porsche needs more intervention anyway as it is inherently less stable, due to the engine placement. See below.
2) The Porsche is effectively as fast as the Lambo in real world conditions.
That's what I said. So why do you want both?
3) Your information is incorrect.
The engine and gearbox bring all the weight at the back of the car, which leads to heavy oversteer, exacerbated by the light front end and the additional traction from the weight over the rear wheels, which are driving the car. Electronic doodads can tame this but they don't change the basic fact of it. Your information is incorrect, and, in fact, missing.
4) I have a 911 Turbo
Bully for you. I assume it's a new one as it has AWD, so enjoy the depreciation on that bad boy. And the fact that you bought the wrong car.
LB, you really are a massive geek.