Thanks for resurrecting - i didn't see the question. Foxtrot, the flavors were captured well, but they were much more smooth/mellow. If you're looking for a bigger flavor than what cold steeping "normal" amounts yield, you can up the amount. So, the flavor for 1/4lb black and 1/2lb choc might taste like less, so you could up a little.
Bakins - i think either method should work with equal results. What i recently did with a stout was cold steep all the dark grains, then throw the whole thing (about a quart) in with the grainbed for sparging. Problem was i didn't think ahead and i threw it in during the last (of two) sparges. so the cold steeping portion didn't get rinsed as well as it should have and the beer as a whole took on less of a stout quality and more of a complex dark amber ale. If you cold steep and toss in during the sparge, you won't have to adjust for pH (with regards to dark grains), as you should have already done that for your normal sac rest conversion.