Ann: Massive Nickel-Copper Sulphides at Stricklands-SGQ.AX, page-207

I have noticed companies like Novo Resources at Nullagine announcing the quick results possible for geochemistry -presumably including gold. Comments above indicate laboratory analysis is the only real way to evaluate gold grades ? People I know question the validity of in field XRF ! I have not completed my research yet but there seems to be a lot of respected suppliers of this equipment claiming their units are indeed capable of immediate field analysis for precious metals at the same degree of accuracy as fire assay and at far less cost. Does anyone have first hand recent experience in this regard ?