I watched it twice, eager to learn (and enjoyed the birdsong in the background), but I don't think I got much value from seeing a highly-tweaked setting on a GPX fitted with 11" coils, being compared to an SDC with its fixed 8" coil, running at its basic sensitivity level. Yes, big coils can go deeper than smaller coils, but so what? Surely it would have been more relevant to test the higher sensitivity levels on the SDC, to see whether these can help make up for its coil size limitation.