I live right smack in the middle of Canada. A Canadian prarie winter can be very severe.

No, you do not absolutely "need" winter tires.
But for that matter you don't need a 4x4 either.

I am with Old Army on this subject. Sure 4x4 gives you twice as much traction, BUT twice of nothing is still nothing.

My FWD Accord on winter tires will run circles around my Xterra with all seasons (longtrails).

Now I am not talking about 30 cm of snow. Naturally 4x4 , and a higher ground clearence will out perform the Accord.

I am talking about icey conditions, driving up my drive way which is on an incline.
Honda wins easy.

All the 4x4, AWD, traction control, LSD, mean absolutely nothing if the 4 contact points on the road have no traction.

For the winter I put on a set of Michelin Latitude x-ice tires.

There is a huge increase in traction.

People that say (not knocking anyone) you do not "need" winter tires, and tell you your all seasons will do, simply have never driven on winter tires. I was one of those people.

Once you drive on winter tires you will never drive without them.

It amazes me when I see people shelling out lots of cash on leather, abs, ebd, traction control, navigation, dvd, boom boom hear it for blocks stereos, but cheap out on winter tires.

Since you are only driving on each set of tires for 6 months, they last almost twice as long.

Our winter was unusually warm last year, and a lot of days were hovering around 0 degrees.

One day we had some freezing rain. I came up to a 4 way stop. Thank god I had my winter rubber on. I was able to stop, while mr. minivan on all seasons slid right through. We would have hit had I been on all seasons.

As far as I am concerned avoiding just one accident more than pays for the tires.

As for studded vs non studded, you would be surprised at how well non studded tires perform.

Stick with non studded, and just use tire cables if there is some freezing rain.