hey, I'm on NASIOC 
are you asking about how is it better in snow or on the track, or what? Obviously the driving dynamics are going to be different when half the power is going to the rear drive wheels (whereas the MS3 rear wheels are just along for the ride).
The dynamics are different for handling. The AWD obviously gives a better capability for launches, particularly on slick surfaces, due to weight transfer.
Also the fact that with FWD car all power and steering is being provided by the front wheels, whereas in an AWD car that is not the case.
I hate to sound simplistic, but without knowing the context of your question, it's hard to know exactly what you're asking. The MS3 on an autocross course or track is pretty comparable in times to the new WRX, but if snow or rallycross is your concern, then the AWD, even with open diffs, is going to be superior to a FWD with LSD....
me = previous owner of several FWD cars with LSD and currenty an 09 WRX, by the way.