I tried reproducing the look of basic sumi-e brush strokes last night.
Sumi-e is the Japanese word for a Chinese-origin artform. Calligraphy and other images are committed to rice paper with a brush, using a water-and-charcoal ink.
I liked the look of the oil brush with a thin paint, especially when the paint started to run out and the grain shows through. But in sumi-e, you can sustain that "almost running out" tone for the whole stroke, thanks to the way the ink interacts with the paper and the brush serves as a reservoir for ample water. This kind of very-long-unloading behavior will be important for any water-based ink, as opposed to the very-fast-unloading behavior for oils.
I liked the shape of the soft magic marker strokes, in that there was a very simple linear relationship between width of stroke and pressure, without affecting the darkness of the stroke. It was easier to manage a stroke's width during the stroke.
In neither case was the tight-cornering behavior ideal. Since each stroke is subtractive, you don't want to make corners with two separate strokes, but when you turn sharply with the current tools, you often get a funny shape on the interior side of the corner, as the tool's rotation changes quickly.
Just jotting my notes since I was thinking of them last night. I'll work out fake labor-intensive ways of emulating sumi-e strokes, since I actually have no talent for the real media but love the looks. If anyone has tips, I'm all ears. Or eyes.