- Sculptris is based on triangles. ZBrush is based on quads. That would make it pretty hard to absorb dynamic tesselation (which requires triangles) into ZBrush.
- Sculptris DID get a major update after it was acquired by Pixologic. In fact, that update included GoZ -- something that would have been a real waste of time implementing if the intent was to do away with Sculptris.
- Dr. Petter is now with Pixologic and his focus is on Sculptris. He does not work on ZBrush.
- It has only been 9 months since the last Sculptris update.
Pixologic does not see Sculptris as competition. We see it as an easily accessible introduction to the world of digital sculpting and painting. Because the skills you develop while learning Sculptris dovetail nicely with ZBrush and GoZ facilitates moving betwee the two applications, it is Pixologic's hope that when a Sculptris user feels ready to take the next step he or she will give ZBrush serious consideration.
It really is that simple.