Never mind. I am a blithering idiot. When I changed user passwords in JXplorer, I clicked OK in the password dialog, but then forgot to click Submit in the main window, so the changes never took effect. Tried againd and did it right this time, and everything works just fine. Good news is that I can attest that integrating Drupal with OpenLDAP is trivial, as long as you have a few brain cells left to spare :-).