How does locking the Transfer Case in a 4WD Sports Car change the Dynamics?

[6./ZG26_Klaus_Mann]

In my Head it should make the Car a bit more unstable, as the Rear Wheels are Forced to Spin faster than the Front, thus breaking Loose more readily. 

[ZachariasX]

Locking the center differential will make it corner differently, a slight sort of understeer is the result as the car will not like to drift just on the back wheels.

[Gambit21]

A spinning wheel has no directional integrity - so I would avoid this.