Well, I have given up on this. I can see this being very useful in the right application and indeed the web site now makes more sense after using the program in terms of applications.
It does not create previews or indexes, and relies on using the built in previews I assume. But it can search and add IPTC data etc, which it seems to only embed in the file.
It has a pretty sophisticated Raw editor and output options, which all seem to be built for speed. A sort of Photo Mechanic with better search and, much better, editing capabilities.
The idea given on the web site of it rapidly searching millions of images certainly wouldn't work on my machine as it took many minutes to open a folder with 2000 images. But I can see the value of it, just not for me. If you needed to go from ingested files to high quality output, very quickly, this would be a very good tool.
I would still be interested in hearing from anyone who actually use it, and what they use it for.