I dunno about all this fancy-scmancy stuff on a winter bike..
Internal geared hubs are great, if you have 135mm dropouts....
Disc brakes? Lotta money to expose to the salt spray around here..
Keep it simple-a fixed gear (at maybe 60 gear inches) with studded tyres is simple, light, cheap, and has fewer things to break. Fixed gear also allows you greater control on the rear wheel.
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Je vais à vélo, donc je suis!