@ozbucheronIf stripping ratio changes, then it is relative to grade and commodity price; if the mine is economical. That is the point of the SRmax; to ascertain tolerances for strip ratio, grade and metal prices to see how robust the project/mine is.
The SRmax is what they teach in mining economics at universities. It is not my metric; however the method for deriving the unit waste cost per ton from the Prospectus/PFS is mine.
The pro-forma income forecast divided by the number of shares is also my method.
Perhaps we can build a better metric than the SRmax; however I don't see the need if I have my pro-forma income spreadsheet to use it in-conjunction with the SRmax.