I've mostly only ever shaded with charcoal and specifically chosen positive space, leaving negative space largely unfilled.
In what ways are doing cell shading different from normal traditional shading?
One reason I had always avoided it, was I'm not sure if it's going to contrast with charcoal shaded art, which carries its own visual aesthetic at times. ( Especially when you smudge it. )
Most of my dark art in the past has been with homemade burnt cedar. I choose cedar, because I feel like it burns more thoroughly, smells better, and you get more bang for your buck.