Dragging upstream can indeed be very productive. Takes a heavier jig and a slower drag speed, but it definitely works…especially when the water is as cold as it is now. It is also probably easier to control the boat when dragging upstream.
Even with all of those positives, I still spend a lot of time dragging downstream with light jigs and plastics in the winter. It seems like I catch larger fish dragging down and sometimes better numbers dragging up. Also helps to drag both ways during the course of the day, just to see if the fish prefer one direction over the other. They certainly have more time to inspect the presentation when dragging slowly upstream, rather than being forced into a reaction bite when a bait comes cruising past them downstream.
Summertime, with light jigs and bait, is almost entirely a downstream presentation for me.