Snow and Ice are two completely different animals. A tire could be excellent in snow, and very poor in ice in my opinion.
I hear a lot of people post the GY Duratrac are excellent in snow, but I have not read any comments about ice.
Truth be told, not many tires can have a good balance of tire wear, road manners, and snow performance and be good in ice too. Ice is a tough nut to crack when it comes to tires - very few can truly be rated as "great" in ice.
...but the DT can be pinned for studs, so if ice traction is truly a concern then they have a leg up in that category, while still being great in mud and snow.