As a moisture absorbant placed above the inner cover and inside an empty super, dry sugar has performed exceptionally well for my bees. Its a win-win.
Of course I place considerably more than just a 'handful'-its more like between 5 & 10 lbs, so its a few inches deep, and also covered w/ 2" rigid insulation.
By Spring the sugar is hard as a rock (from the moisture absorbed throughout the winter) and my less well-off bees chow on it until the first flow or it becomes warm enough to feed syrup.
This week I will be covering my hives w/ 1" rigid insulation for the first time after much convincing discussion and debate from this site ;)