Well, I looked at TTs tool and I cranked it up... after a min of watching the file count grow... I opened a terminal window and ran a "find" command piped to "grep" and piped the result to file. The "find" command had identified 500K files before TTs tool hit 15K.
I think my solution of shelling out and using the native command was a good call. Problem is...once I identify 500K files -- now I need to open each one and process the XML data contained therein. I ended up doing the operation on my old HFS+ Macbook just to get my first task done. One of my tests runs was against 1.2 million documents - and the other was over 5 million. Performance varied a bit over the course of the operation -- but I think I was averaging about 300 docs/sec using Xojo's XML classes. -- Not hateful. Hopefully the problem isn't an APFS limit -- and it's just a matter of Hooking the new "drivers". I'm concerned that Christians's MBS code while FAR superior to Xojo's Folderitem class for the operations I was using -- still falls short on APFS when compared to HFS+. Nothing I like better than to see a $4,000 Laptop get it's a$$ handed to it by a decade old system with an ancient file system.