I have not bought specifically their black. But I have bought their white by the bolt, as well as some other colors in yardage. I prefer to cut my own strips and squares as it is more economical. Their Dream cotton is really a nice fabric and I believe a heaveir weitht than the Kona. I can't say that I think it frays that much. There would be some when fabric is cut straight as opposed to pinked edges, but nothing that really bothers me.
I also like their Blended fabric when I don't want a true solid. They have a modled look and are more attractive in my mind when chosing colors (not necessarily blacks or whites) They also have a good weight to them, but not as nice a hand as the Dream cotton. I have purchased Kona solids, but other than their vast color offerings, I really prefer the Dream cotton. That's my take on it anyway.