I cycle-commute all through the winter on unlit country lanes (have done for the last six years). I have a decent dynamo setup and the full compliment of legally required reflectors, plus reflective ankle bands, reflective trips on my cycling jacket, reflective bits on the back of my shoes and gloves, and reflective bits on my rack bag. I have never had a problem with drivers not seeing me, and there is no difference in the way drivers act around me during the winter nights or on sunny summer days.