Search Dave Coleman on youtube. And you can watch 'tests' comparing various AWD vehicles. You won't find any actual tech articles, just supposition by car geeks. Most of which is wrong. :|
The bottom line is that we don't have limited slip differentials, so mostly still a 2-wheel-drive auto (one on front axle gets full torque, one on rear axle gets (some?) torque).
FYI, my 2000 Outback had an LSD, and it made a huge difference in deep snow, pulling a snowmobile trailer and two sleds (on lake ice).