I think it depnds upon a number of factors ...

I've run down the river a number of times in the dark, usually it's something we only do in salmon season when we know positioning / first light bite is going to be a factor.

If it's a piece of water you haven't been down in a bit and there could possibly be additions to the river / other changes ... then it's probably not the smartest move in the book. If it's a piece of water you know very well and your boat handling skills are very good, then I don't see a lot or problem with it.

I can still still see the white knuckles of Gusty when I took him and his partner through a couple of miles of the 'Duc in total darkness (we did have a spot) at about 6 boards. They'd been through there in the daylight with me before, and knew some of what we were going through ... I think it made them a wee bit anxious