BBW is kind of like playing with random slates in an attempt to get a finishing stone. You look at them and they seem like they will be really good for the intended purpose, but then testing usually shows otherwise. If something is dead slow, you usually want some sort of concession in the form of absolute fineness but they don't get there. They have positives in the sense that a lot of them have genuinely nice feedback and are really not damaging at all. You want the redder stuff, generally. I only think that dark one I have is exceptional because the coti it is bound with is.