I ended up with 6.5-7" of depth, I was expecting 9" but was told by the PB that 6" was the norm and his Suntan shelf was 6". He also told me that you might have to have a step down (per code) if deeper. As previously posted if you can not live with this have them change it now and don't worry about the gunite. It still will be strucually sound. You might want to measure from the gunite to the coping line and post back, take an 1'' to 1.5" off for the waterline.
Here is a picture of our finished Tan Shelf.