I recently picked up a couple of Prismacolor pens in the brush tip and the super fine .005 tip in Brown. I used them to do this drawing on a page from an old ham radio log book.
First, I would like to say that I love the color. I use Prismacolor pencils a lot, and I always find their products to be of excellent quality.
That being said, I did feel like the depth of the pigments in the brush tip vs the .005 tip were significantly different.
The pigment in the brush tip pen was deep and rich. In the ultra fine tip pen, however, the pigment was much thinner. It could be that having a heavier pigmentation would clog the ultra fine tip, I'm not sure. At any rate, the finer tip was a little disappointing in its depth.
If you look at this closeup, you can see the differences. The glasses, and certain parts of the eye that were done with the brush pen are deeper in color. However, I could not take the ultra thin pen and build up to the same intensity,
Additionally, the ultra fine tip was quick to dry out, as you can see by the strokes on the left side of the closeup. It would seem that the ultra fine tip does better with shorter, slower strokes as around the eye. I would say that it would be better either with a smaller drawing or a drawing made of shorter strokes.
I did like the pens, though, and will post a new piece with them soon.