I prefer black powders too because of the color and taste. I've used santa barbara chocolate cocoa powders and this is what they say about black cocoa and it's acidity:
Regarding Black Cocoa Powder, what is the Dutch Process?
Black cocoa develops this dark color from roasting the cocoa beans and alkalizing them. Alkalizing cocoa to different degrees allows color variation so your cookies, pie crusts or cakes can have unique and pretty chocolate color variation of lightness to darkness. Dutching also reduces the natural cocoa bean acidity so the cocoa powder won't react with baking powder in a recipe. Dutch process also allows a variation in flavor of cocoa powders.
You'll find Black Cocoa Powder to have a dark roast cocoa taste, earthy and heady with lighter fudge like nuances and a trailing floral flavor. Having a range of cocoa powders is popular with gelato makers because each cocoa has a unique and individual chocolate flavor so a fleet tasting of chocolate gelato can be presented for a fun and memorable experience.
Typically the lighter the color of the cocoa the flavor will be more acidic, fruity and with low fudge notes. Medium brown cocoas will tend to have some fruit note but the fudge flavor becomes more pronounced. With red cocoas the fudge flavor becomes less pronounced and the fruit flavor tends to give way to subtle floral hints. Black cocoa offers the most robust experience characteristically earthy with not as much fudge like flavor. The color and smell are the most intense aspects of Black Cocoa and as a result work wonderfully in a mud pie recipe or in chocolate hazelnut gelato. (original text can be found here)
