Selfishly, as a K20 user I am glad to hear the slot drive is gone (at least from one offering) hopefully we can look forward to the same thing from the 60-250
I've not used a lens that had only an SDM motor and no slot drive to know if the MF feel is improved by doing away with the slot gear shaft, but I'm interested to learn it. It would also seem possible to add some extra throw range on the focus ring without having to consider the strain on the little slot shaft as well. If the latter two points are unaffected by its removal, then one can only hope it offsets the cost of the motor somewhat.