I have had great results adding my dark specialty grains at vorlauf/sparge....it's a lot easier than cold steeping.
I did the cold steeping until I discovered Sinamar. Once I found that someone had done the work for me, I quit using cold steeping.
What volume do you buy that in? I did see what looked like maybe 4 liter containers at Russian River.
I just buy the 4 oz. bottle, but I've seen the 4L jugs at Rogue, too.