It is hard to beat Painter for simulating paint brushes of all kinds, and the cloning on the fly technique; however the new bristle brushes in CS5 are pretty cool and the new mixer brush is really quite unique. You can set the wetness of the canvas, and mix the pixels on the canvas, but also add another color at the same time, to whatever degree you want. This brush is one of a kind as far as I know, it was the brush I've been wanting for some time. I'm still learning the possibilities with it. CS5 is a major upgrade in many ways and is well worth the cost, I highly recommend CS5 for this new brush alone, but there are a lot of good new things too.