The folks at my LBS are recommending no knobs, no studs, but a grippier tire that will do better in wet and sometimes slushy conditions. The truth of the matter is that Boston doesn't get a ton of snow...wait, stop throwing things at me...Boston gets snow, and it can be frequent some winters, but what's not frequent is snow remaining on the roads day after day. The day after a snowstorm, it'll be clear and wet; the day after that, it'll be dry. So, I'm thinking what I'm going to gear up for is more wet roads than ice and snow. Depending on how far out of town you are, though, the mix may be different.