Bruce Silver covers Roubroo on his blog.? It is interesting because it attempts to address ad-hoc changes to a process, without abandoning BPMN.
What happens under the covers is Roubroo creates a new version of the process definition and migrates the current instance, but the end user doesn?t need to see all that.? The backward token injection (while retaining all of the downstream token processing requirements of the BPMN 2.0 spec) is the hard part.
Looks like what they attempt to do under the covers is reasonably complicated (versioning the process definition, etc.) - but they try to simplify that for the user.? I like the design principles involved but I think this is something you have to experience yourself to see if it works for you.
At BP3 we have some "similar but different" ideas for how to tackle this, and we'll have to return to the topic later after we have a prototype fleshed out.