An AWD with 50/50 bias in weight and torque is perfectly neutral, and you will not be able to force over or under steer. My V70 will eventually oversteer by a little bit due to the suspension setup (stock).
Avoiding an obsticle in the road with your foot off the gas will result in understeer in the V70, real world. With power on, it will oversteer. Neither conditions will be as pronounced as the FWD or RWD cars, because the wheels will not loose traction.
In your initial hypothisis, all 4 wheels hitting loose sand (or ice), the car will slide sideways in a neutral slide.

The big SUVs doing sudden lane changes and flipping over are because they are top heavy. Never buy a car/truck that is taller than it is wide :)

Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)