I'm working on a small TC with graphics drawn in pen, pencil, crayon, etc.
They way I see it, the pros and cond are:
Cursors, and targeting don't work so hot on light backgrounds.
Looking like the objects are drawn directly on the background is cool from a thematic standpoint. Different "papers" for different systems.
Some stellars can be coffe rings, paperclips and such.
With colored backgrounds, I'm still limited to a narrow range as the anti-aliasing on the drawn edges needs to stay blended or it doesn't look seamless anymore. Whereas having a single black background doesn't have this problem.
Perhaps you have a hybrid solution?