No, I don't think studded tires are necessary. I reserve the right to change my mind next year, though. That's why I'd prefer the Surly. It gives you the option of studded tires if you later decide to go that way.

Personally, I wouldn't get rid of both your existing bikes. I'd keep one for a bad weather bike and spare commuter. Then, I wouldn't have to worry about the tire width of the nice bike.