Well done, Klaus!
I'd like to know if you plan to invest more time on it in the near feature (no time constraints, just the intention to keep it high on your "software development" to-do list).
Did you consider the "resources" (and related costs) needed to complete a task?
They could be, for example, equipment to buy/rent, logistics (room, transport..) and people. Well, talking about people, one thing I always hated was the use of the word "resource" applied to them, altough it's of common use. Anyway, on a task we could have hired personnel, external specialists (payed by hours/day), consultants..anyone working full day or part-time.
All that will add to the cost of a task/group and sum up to the total cost of the project.
Adding resources (e.g when you risk to exceed time constraints) will invrease total project cost and eventually take it out of budget.
Thank you again for the great job you did so far.
udg