I agree completely Paul.
The three surfaces are as different as G/F, Good and G/S are to each other. I would also say Chelmsford is very different to the other Polytrack courses as well. Last year it was like G/F ground but they have done something to alter the texture, probably harrowing deeper. It would be a great help though if the three types were highlighted in some way, as I have to go through each run manually to see which surface they have been run on.