[Flieger]

The axis for polar moment of inertia goes through the mass center, so on a 911 the mass center is further back than on a 914. This means that the 911 wants to rotate about the rear wheel more than a 914, which would want to rotate around the middle.

The way I see it, this means that the 911 should go deep into a turn, trail braking, slow down and take a late turn-in, where it can use the quicker angular acceleration of the front wheels about the rear to point the front end towards the apex and then "shoot" towards it, using the rear weight to gain traction, stop the angular acceleration, and get down the track fast in a straight line.

The 914, conversely, should carry speed on a wider arc through the turn, with the wider arc shifting the pivot point out and forward from the rear inside tire.

This seems to be backed up by the driving styles adopted by 911 and 914 drivers.

I would conjecture that weight, power, and tires being equal, a 911 might have an advantage on autocross courses where there are long-ish straights with tight hairpins, and the 914 would be better at Willow Springs, for example.

The big thing is that having weight within the wheelbase means there is no "leverage" of weight off of the front wheels. The weight contributes to traction on both front and rear ends.