Thanks, EldritchCellar. PPC G5 -- impressive! RSRConv will also convert .rsr to .png and get rid of tumbnail.db files as well. I have found a few freebie .pz2 files specified as Windows-only that reference a displacement .tif for DAZ's Michael 4 that apparently doesn't get installed on Macs (at least not on mine) and will kick off a "please locate [file]" search, but that's a minor irritation that can be worked around. Anyway, you're right, most items will work, albeit with some tweaking occasionally.

Keep up your good work!