We were reviewing both Stardust and Activiti. The Stardust build was extremely complex and we could never get it working as per the online documentation. We found Activiti to be much more mature and reliable so far, so we dropped our Stardust analysis. It is too bad because it has some great features like a simulation engine. It just seems to have "too many cooks in the kitchen" lacking the level of coordination required to make it seem like a single, uniform project.