Originally posted by artrasa But I have to say that I would be a bit hesitant to spend money on lenses equipped with SDM focusing systems in future after reading this
Note that issues with the SDM mechanism have been limited to a now older range of lenses, primarily the DA*16-50, DA*50-135 and DA*60-250. New lenses like the DFA 24-70, 15-30 and 70-210 are listed as SDM but supposedly (almost certainly) use a different motor completely. It is unfortunate (IMHO) that Ricoh used the same terminology considering the poor reputation of the 'SDM' term.
But as UncleVanya states real numbers are hard to come by, and likely the actual failure percentage was not nearly as high as forum posts might indicate. I would have no hesitation in buying a new SDM lens, in fact I have all three of the DFA ones. However, buying a used DA* one I would be cautious. But of those lenses the two most commonly mentioned (possibly because they sold the most) are the 16-50 and the 50-135 both of which can be converted to screw-drive which in my experience actually works better and faster than the SDM in those lenses.