thanks luke, but not sure i quite understand: virtually every single mirrorless from sony, fuji, oly, panny and even leica, across FF, apsc and m4/3 formats have mechanical shutters. all those companies sell proprietary lenses specifically for those systems. all accomodate legacy glass--including those made by the manufacturer! same is true for pentax medium format, insofar as mechanical shutter and pentax legacy glass is concerned. so i unfortunately remain confused about this choice, which, btw, i think has more to do with wanting to incorporate a lens based leaf shutter than another proprietary advantage...what i remain confused about is the advantage of such a system in a mirrorless format, and the other benefits/detriments lack of mechanical shutter has on this system now and going forward.