If anyone is undecided about whether to get winter tires, he or she shouldn't be.

1. Winter tires can make a significant reduction in braking distance relative to all season tires, especially if the all season tires have a performance oriented compound, as they tend to provide very poor winter traction.

2. The added cost in the wheels, installation, and possibly storage is secondary compared to the safety benefits, and the cost of an avoidable accident (e.g. insurance premiums, deductibles, repairs, injury, death).

3. Using winter tires preserves the life of your summer tires, and the condition of your summer wheels. 

I have used Nokian's "all-weather" WRG2 and WRG3 tires. They are better than all-seasons, and even better than some winter tires I have tried. They may be a good compromise for those who cannot be bothered with a winter tire change, e.g. due to storage space, cost, the limited mileage they drive or other reasons.