Neither will hold a candle to studded tires on ice. Metal studs will dig in and grip while rubber will just slide over the top.
The Pisgah has more aggressive knobs that will handle deeper snow,the Dartmoor will roll better on bare pavement. For snow,use this to make your choice,but for ice you def want studs.
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C'dale BBU('05 and '09)/Super Six/Hooligan8and 3,Kona Dew Deluxe,Novara Buzz/Safari,Surly Big Dummy,Marin Pt Reyes,Giant Defy 1,Schwinn DBX SuperSport,Brompton S6L/S2E-X/M6L-X/S12 T Line