Dave,
Last night I worked through the data model and confirmed that the photo album application does in fact use the CR. The only thing I can see that differs from your suggestion is that albums are of content_type pa_album instead of the more general content_type content_folder.
As the data model is basically sound it seems a shame to discard so much proven code. I think it would be ideal to have the existing code as a means of entering and organising images complete with Ajax ui already built, and be able to export images to an xowiki instance such that the exported images appear as xowiki::File entries. This would preserve the current bulk upload capability whilst allowing images to be used in xowiki.
I have mapped the data structure which I will post below for reference.
Richard
