Cotton, wool, silk, and bamboo don't beard a lot, do they? I just put a black Hobbs 80/20 batt in the quilt I'm quilting right now even though the greys on the top go very light. About 40 % of the top is black or very dark and the back is dark, dark charcoal - almost solid. That's what helped me choose black batt... The back, and I just wanted to do something different...
What are you putting on the back? And are you considering a poly batt?