Once I got studded tires I don't know how I survived for the years that I rode without them. Now, I wouldn't ride without studded tires. Last year was the first year I didn't fall in the winter because of ice and we had lots of ice. These were the 622 version so I can't speak for the 349 version but I suspect they are very similar. The studs sit on the edge of the tire so that when pedaling straight you get less rolling resistance. When cornering the studs dig into the ice or when you slip sideways the studs grab the ice and you stay upright.

It all depends on the type of winter you get. We get snow and lots of ice from snow melting and then refreezing at night. If I start riding my Brompton in the winter, then I will definitely get a pair.