Are HT still buffing their chisels to the Nth degree? In which case, personally I'd hesitate - flattening the back (or face, depending on your nomenclature preference) is a major pain in the proverbial when the edges have been rounded off during the buffing process. Some years ago I diligently worked my way through doing it on a HT cranked neck paring chisel - and then sent the others I'd bought back to the vendor on the basis that I only had a certain number of years on the planet.