I truly like the specialty paint by Pebeo, but there is a learning curve to using it on polymer clay. Last month at the Southern Connecticut Clay Guild retreat, Clay ConneCTion, I had the opportunity to dabble both the Fantasy and the Moon paints. I truly dabbled the paint on to baked inchies tiles. Clay thickness was number 1 on an Atlas pasta machine. The paint was applied with the tip of a dollar store wooden screwer. After drying i noticed that some of the tiles curled up at the corners. So my theory is that the paint does pull the clay as it dries and retracts. The retracting of the paint may cause the clay to crack.
I went on to try the clay on a thick piece. Advice: make sure the layers of clay are really pressed together, because the paint is going to pull at the clay. Here are a couple of images of my experience.