I've heard that steeping the dark grains in porter and stout recipes rather than mashing generally results in a smoother, less harsh flavor than adding the dark grains to the mash. (This seems to be my experience - my extract porters and stouts made with steeped dark grains and amber extract have generally come out better than my all grain versions.) I'm wondering whether, to maximize flavor extraction, it makes sense to do the steeping in the sparge water rather than the collected wort. Has anyone tried this?