Should the Polytrack have its own Merit Ratings

Should the Poly track have its own merit Rating

eg- The Grass and the Sand have their own ratings as horses run differently on different surfaces
Some horses run very well on the grass and some don't run well on the poly and so the other way around..... when racing moves surface, you get scratchings with the reason "change of surface"

In my opinion... I feel that their should be different ratings for different surfaces

Any other opinions on this???

Only happens in the UK if there is irrefutable proof that there is a difference