Your neighbors missed the point. What was said is that with the hard coating on the threshing elements and tines if you run a bunch of rocks through the machine it will rough up the surface of the parts. Rough surfaces are never good for gentle threshing and with the extended wear package where all the surfaces of the parts are harder it takes longer for the roughness to get smoothed down again. I was told it was no worse than chrome rasp bars in a straw walker machine. If you got along OK with chrome bars in a walker you'll probably get along OK with the extended wear package in the STS.