Learned from someone on IRC that there's a trick to getting Copics to make large areas of uniform color without streaking - spray the paper down with a mist-bottle. My first experiment with it has gone reasonably well so far, but I've got preliminary results - Uniformity Matters. The more even your mist is, the less it's going to randomly bleed, since the bottle I have isn't as even as it once was, and the tendency for ink to bleed over into other areas was essentially random. Also, it tends to make them go on wetter, though not quite as wet as Prismacolors. Lastly, it does not eliminate banding by itself, but it gives you a little more time to keep the color front dry, which in larger regions is simply impossible (and larger complex ares, where you don't want to color over something else and using the 2" wide Copic marker is impractical) - making them go from flat-out impossible to merely difficult, as they would be with Prismacolor or Sharpie.