Recently had the same problem again (and forgot the solution), but this time around I found a GUI program before I remembered this thread. Apologies for bumping this long deceased thread, hopefully this helps someone else who googles for this.
In case anyone doesn't want to use command line, a non-command line freeware program does just what I wanted - it converted the DJVU to PDF, preserving the image layer and TOC but discarding the OCR layer:
STDU Converter. It has lots of options but I just hit Convert and it did what I wanted, and gave a fairly small output file too.