i agree to what u say, but to develop something big i need to know the specification of ACTIVITI engine… for example:- how much load it can take… and if a private firm wants to own ACTIVITI server for the execution how to proceed …etc etc..
We havent done any load testing, but if you understand the architecture of Activiti you will see that it has a very minimal overhead and is cluster-ready.
But we are always eager to hear your own experience with trying to match Activiti with your requirements.