You have a lot of really nice work. And, you do a lot on darker paper. I only recently discovered using that paper from a Lynda.com drawing course project. It's a nice change from white. I have tried both brown and gray. At first I was using the insides of cereal boxes for the Lynda.com course projects. It has a nice texture. But, you can't get a really big size. I eventually broke down and went to the store and got a pad of dark brown stock.
Do you have any advice from what you've learned from drawing on the darker stock?