Er, when I am fussing over the balance, I look to my beta & alpha amylase rests - both temperature and duration. I get quite god control over maltyness, dryness, and sweetness. I get most of my fine bitterness control from the dry or wet hop in the secondary.
So this discussion makes suspicious of my methods. For and Imperial Porter, we used a 30 min 131 F saccrification rest (almost down to protease) and get this 75 minutes at 152 F (lower than most infusion methods). We really dried the Porter out. A strong bitter sweet chocolate mouth, followed by a very clean, ordinary style, finish that leaves you wondering about the intensity of the mouth.
Can ph have that much effect on a step mash process?