Been using the SDC for a few weeks now in Australia & 0.03 grams might be the magic number? My smallest has been 0.09 gram but went out with a mate to an area in NSW (Stuart Town) & he pinged the smallest I have seen so far which strained the scales at 0.03 gram
The SDC has been handling the ground well over this side of the pond too & I have had very few issues with "hot" rocks to date. Haven't had any falsing at all with hitting rocks etc. with the coil.