Remember that the purpose of brewing salts is for flavor- not for pH adjustment. Acid or base is used to adjust the mash pH, if needed, and then the brewing salts are used for the flavor impact or to assist in clearing. For example, a calcium level of 40 ppm or more is helpful in keeping beerstone from forming, as well as assisting yeast flocculation.
Think of brewing salts as table salt and other spices in food- "seasonings" for your beer. Chloride improves the mouthfeel and provides a fullness, while sulfate enhances a dry perception. A little is often a good addition, depending on what you're making.
Many German lagers are best with very little mineralization, and RO water or distilled water is great for some of these, with a little acid malt or acid in the mash if needed for pH adjustment.