In 2006 I bought myself an off road Susuki DR-Z400. Living here in Scotland this bike was the best all rounder I ever owned and I used it all year round - sun or snow.
Unfortunately it was stolen in December, 2008 and I decided to buy the newer DR-Z400SM.
The SM is just as solid as the off road version, but in snow with road going tyres it was hell. Recently I fitted it with Avon Distanzia trail tyres and it has much improved the handling on the icy roads of Scotland.
On the road they seem to grip just as well as any road going tyre also. However they are rather expensive, but well worth it for your own safety.
One problem we seem to have with these bikes in the very cold conditions is carb-freeze. The SM did suffer from this problem in the beginning but now it seems to have cured itself and has done 7000 miles in 12months. In all weathers without a single problem.
It is a great bike for touring Scotland during the winter months and a great traffic-buster around town.
They are really solid built bikes and well worth their weight in gold.
Attached photos are on a days trip around the snow covered mountains of Glenshee on 20-01-10.