Do you think drops will help you better than flat bars on snowy/icy stretches you sail across using only rear braking and front steering to avoid wiping out? I would switch from flat to wider flat rather than flat to drop for that scenario. Of course sailing down a narrow icy descent that people are trying to climb on the other half you might not want to be wider...

The biggest change that helped me in winter is switching to single-speed. It's not as consistently cold where I am as you get so maybe you won't get your derailers as consistently slushed up as I do. IGH would have the same advantage as SS I would think if your topography or prevailing winds aren't suited to SS.

Clipless pedals are not great if you are stepping down onto slush/snow either, hard to get your feet back in. Platforms and comfy boots are the way to go there. Which introduces its own set of challenges, keeping the laces out of the chain.