Torque split has nothing to do with weight distribution, engine orientation, suspension, etc, and everything to do with mechanical gearing in the differential and drivetrain. A bevel gear differential is by nature, a 50/50 split, not including the biasing effects of any lockup/LSD device.
Also, I'm not sure which Subaru you are talking about, but all of them, even the STi, understeer like a pig from the factory. The STi does have a smidge of power-on oversteer because of the unequal torque split, but nothing compared to a RWD car.
The STi does *not* have "front assist". It has a fixed 35/65 split center planetary gear diff that is operating full-time, coupled to an electronic clutch that can lock the front and rear axles with an identical arrangement to our VCU or the Evo's ACD. The Skyline does not have a full-time center diff, just an electronic clutch between front and rear.
To put it another way, an Evo VIII ACD with a Cusco planetary center (35/65) would be functionally identical to the Subaru's DCCD system (except for the controls, sensors, tuning, etc)
4WD cars don't really have the same kind of direct power-on over/understeer that 2WD cars do - almost all of the handling behavior is passive, and due to suspension and weight balance.