The issue is just the total number of jpegs (and in many cases their associated tifs, raws, and xmps), the total size of all of these files -- ~200GB, and the speed of my network attached storage. I suspect that if tried to do it in one go using PM, my system would choke (but it might not be obvious for a while). Certainly I could do it if I broke it down into small enough chunks. But it seemed to me that the ImageMagick solution might be easier. Once I set it up, it could just chew away; I suspect that the whole job would take several tens of hours.

Bob M