I've only driven my RAV4 Prime a little bit in the snow, but it seems to perform quite well. Certainly slippage will trigger the various anti-skid systems, but I'm not sure how important that is. Another poster, who seemed much more familiar with the Toyota stability systems, referred to what they called "slip and grip". The idea being that "slip and grip" is a very primitive way to create traction control. From what I understand, Toyota goes well beyond slip and grip. Consider the Moose Test. The regular RAV4 did not pass this test, about a year ago. Toyota responded by reprogramming the stability software, and now the car will pass. There is a lot more going on besides slip and grip.
In the various forums and online reviews, there is an endless amount of information about how well a car can get itself off of multiple sets of rollers, or how well it can rock climb, or how well it climbs a rocky/muddy/snowy hill. There is some merit to some of these tests, especially if you are interested in getting into the back country, even if just on fire roads. And you might not get stuck in a snowy parking space. But I think these tests completely fail to cover one important area, which is performance at speed. I don't mean at 100mph. But say, consider cornering at 25 mph on a snow packed road. Toyota does design for this, (as do other manufacturers), but they don't seem to advertise it much. This is Audi's thing- cars that corner faster and handle better because of All Wheel Drive. I know at least a few folks on this forum have tried to make there cars do donuts in the snow, and while I guess it's possible, it's pretty hard to do. Thus showing how a computer can drive better than a human in some cases.
It's easy to put a car on a set of rollers and see what it does. Or drive up a hill such as to put two wheels off the ground. These tests are not entirely useless, and they are easy, (and cheap), to do. But they miss the point of a major aspect of all wheel drive, which is that a well designed AWD system can corner faster and maintain control better than RWD, FWD or a 4x4. However, testing for this is expensive, as you really need to use a track and compare lap times between models. It's a shame though, because the auto manufacturer put a lot of effort into it that largely goes unnoticed.