freiheit:I'm used to working on photoshop; sketch, greyscale and then colors...
Greyscale and then colors? More info please. Do you mean you create your image in greyscale and then use, for example, an Overlay Layer, to add color? If so, then you can do that in Artrage. On the other hand, Artrage seems to me to be more of a straightforward painting application - you use "pigment" to lay down color and mix it with other color using the brushes and palette knife, etc.