My name is Stefan and I am the owner of the school in Silvaplana.
I just say is not trough what many of you are telling. Many fantasy!!!
Our school is now 4 years old and we had about 1500 students in our school. Some days here are a lot of kitesurfers do this fantastic sport. In the middel every day here are about 50 kitesurfer.
In all this three years we have only 3 accidents and only one in the school. 2 brooken lakes and two others all of those kitesurfers are still kitesurfing.
I don't think Silvaplana is more danger than other spots even less, but you have to respect the rocks.