OCD! You'll have to get a spec on the flatness of that abrasive film, and paper.
Personally I feel it is possible, through proper application, to exceed the flatness of dmt, just as it is possible to blow it with improper application.
similar to how we get .3- .5 micron edge widths (the width of the edge is form of "flatness") which is beyond the spec flatness of our stones typically.
(i did say similar:))
Olivia, the granite would do the same as glass. This is a very tricky thing because the grits are rolling around, never embedding themselves as they do with cast iron lapping plates. But if you use the plate evenly it will last longer.