Studs are there for ice and/or hard packed snow. Loose snow, slush etc. - they don't do much. Thread pattern is the exact opposite, aggressive thread / knobs work in loose snow, slush, mud and so on, but provide little help on glare ice.
In city commuting environment, I find I seldom need aggressive thread, but studs are essential. The W106s are narrow (for a studded tyre) and cut through the loose layer.
Last edited by Juha; 09-26-12 at 12:27 AM.