I cold steeped for awhile and made some good beers. But aside from having to double or more the roasted malts ( not a big consideration) and extra effort, I felt that the roasted character was underwhelming on styles where I wanted a roasty beer, ie., porter, stout, etc. I mash all malts together now for the full mash, but targeting 5.5 as my pH and like the results much better. IMO 5.5 pH is the sweet spot. Lots of good ways to get there.