I just demonstrated the system to my head of department and he was intrigued. His view is that it will help us as a department to know what we are doing well. He is not looking to use it against teachers, but instead wants to use it as a method of support. We agree that students and staff alike can benefit in a way not possible before.
The only addition we would suggest is being able to see individual students' papers, so we find out not only where they went wrong but how they went wrong.
Overall, it's an excellent system that needs to be employed by other exam boards. Excellent work, Edexcel.