Yes winter wheels are always a good idea. Do you NEED them depends on you. I know some people that have 4matics and xDrive cars and use only all seasons. I personally would buy winters and do have them on my car.
My buddies don't and they haven't a had a problem. Deep snow is where its gets a little tough, everything is dependent on driving conditions and how experienced you are.
Getting winters doesn't mean you can drive like a maniac like its a dry summer either, its added insurance for the winter.
Be safe and happy driving.
02 CB M3: PSS9s / CCFL AE / Matte Black Grills / Gills / Dinan Exhaust / Dinan CAI / Dinan stg3 tune/ Dice / 18% Tint All around /