In other words, you have to crank up the light source to be 10x brighter to make it reflect as much as vantablack does. I think the returns are always there wh

In other words, you have to crank up the light source to be 10x brighter to make it reflect as much as vantablack does. I think the returns are always there when the improvements are on a log scale like that, assuming you care about darkness in the first place.