Tim, it's generally considered that recreational 4WDs (like the one I have) are NOT much better than regular sedans. In fact their higher centre of gravity is a hindrance (although the Forrester is not as high as others). The authorities will (justifiably) assume that anyone driving a hire car to the ski fields is not a regular mountain-dweller and probably is not used to driving on snow and ice, so they'll insist you put on chains.
It's a good idea anyway, you'll have very precious cargo (your family) so why not err on the side of caution? If conditions are mild you'll probably get away with just engaging low range, but if it snows heavily or gets icy you'll be glad you have the extra grip. Hiring chains is pretty cheap.
Phil from the safety hub about 2 years ago