Ken, FWIW I mash dark beers @ 5.5pH too, all grains together. I feel that the roast character is less harsh and acrid, just overall better at this pH. My theory is that brewers that don't like the character of the dark grains being mashed might well like it if they adjusted their pH up to 5.5ish. Not to say you can't cold steep dark grains and make good beer.
i dont disagree - mine will tend to fall +- .02 from 5.5PH. perhaps a little bump migth be in order and see if i notice any difference.
do you also keep the sulfates low- around 30PPM or so?
I used the Black Balanced profile on an American/Oatmeal stout (Rogue Shakespeare type) and it was great. I used either 'Balanced' or 'Malty' on a more British style Oatmeal Stout (a year or two ago) and it was great too.