@JF - I looked at your ISO tut for the smudge drawn. (Excellent work btw) It gives a nice watercolor or filled look, but in this case I am going for a "hand drawn" or "sketched" look. I have managed to take some brushes made by others and reverse the images (laborious) to get the feel I was after, but I would still prefer to generate my own.

I think that the issue has to do with the ppi settings for the drawing vs the ppi for the image. Obviously a brush at 100 ppi will have less detail when used in 70 ppi drawing, and if vise versa the brush will look blockier. But even when drawn at the same density it just doesnt look right. Still becomes solid in appearance. Ive tried using the brush on a variety of layer types (Normal, Overlay etc.) and the result is usually an opaque right side. Oddly enough, the modified brushes work OK, and upon close examination of the brushes (Opened as image file) the DPI is similar to what I am using for mine (only off by a couple %) so I am sure it is something in my settings now. BUt I still cant find it.