Oh yeah, that script is the bomb. Still not exactly what I need for all situations, but it helps a bunch. It may depend on how you've got your OS set up, but since I use Default Folder X on the Mac I can do a lot of things in a dialog box that the regular Finder can't (it has bigger previews and recent and favorite folders, for instance, and when working on a project I may have all client files of many types in one folder there).
But here's how it already helped: I use tags on all my non-photo documents. System (Mavericks) tags aren't necessary on photos since jpgs and tiffs have embedded metadata including keywords, which serve the same purpose, even though there's some redundancy at times. Sometimes these images are kept with say Word files that are tagged with client names. So if I can find the client file, I'm in the folder with the images I need, even though LR would never to able to find them since they aren't client keyworded. It's sort of like using non-image files as sidecars for purposes of other kinds of searching and organizing. So this script helps; thanks.
But I'm still searching for a system-wide "Find in LR" Applescript or Automator workflow that you could invoke from within other applications. I'll post here if I find one.
And to follow up on suggestions to work from the other direction, is there a plugin that would export a jpg or png to clipboard? The idea being having to avoid export to a folder, go back to application, choose "insert" or "open" or whatever, navigate to said folder, etc.