Duh! Ah ha! Eureka! I was barking up the wrong tree. Thank you, of course a lens has to float to be stabilised. It's not as simple as turning IS off! It does of course beg the question why turning IS off is a feature - other than saving battery life or making sure that tripod shots, panning (or similar) works without interference. So pictures while running is a no-no but a slow shuffle would work.
Any recent progress on manual focusing at infinity? I can already see that the Canon UI scale for MF is effectively useless - it seems to demand MF confirm which I find ironic if not confusing.
There are also all kinds of differences in IQ between the three S100s. Simple variables add up.