Sorry not to get back to you sooner, Ellis, as I was travelling over the weekend. After what you've said, I'd still feel very reluctant to start afresh and would advise you not to rush into it.
The key difficulty is that export as catalog will replicate the existing problems, while avoiding export as catalog would involve a series of manual steps - and mis-steps. It can be done, but isn't it throwing out the baby with the bath water?
Instead I'd encourage you to see if you can resolve specific problems in your existing catalogue. So for example, if "many older images are not in the catalog" then ask if their folders are in the catalogue, if not import the entire folder, if so synchronize the folder (right click the folder in Folders panel), and preferably synchronize a parent folder (if not showing, right click a folder and Show Parent). Tackling a parent folder could allow you to cut straight though the problem of "continually going back and updating and importing". Another thought is to strictly establish "a rational folder structure" going forward, while accepting that photos in the "irrational" folder structure will simply need a bit more metadata - so organizing or categorizing with metadata, not with folders. What I mean here, for example, is that you might populate iptc fields like Job (a favourite field of mine) which allow you to find a project's photos in whatever folder structure by setting it as a column in the Library Filter panel (which also identifies photos to which you've not yet applied a job) or as a criterion in smart collections. This is the route I'd point you towards, and you'll probably find it very close to Peter Krogh's recommendations.
John
