We've discovered that people who have the most success with Gelly's Sty are using it as the body of a piece, or in sculptural work. We've posted a few photos here:
http://www.creationismessy.com/color.aspx?id=2
When you use Gelly's Sty to make dots or stringers which are then applied on top of other colors, Gelly's Sty does lose some of its saturation / hue.
Hope that helps.
Kathy