hi fekhner,
sorry I abandoned that project since I wasn't satisfied with the rendering of the output on the iPad. The iPad (1) has a low resolution display, much lower than the DR1000, and the scaled bitmaps looked rather blurry (giving me a headache after a while). I have now converted all my scanned books with ClearScan OCR (Adobe Acrobat 9 and higher), and they look much sharper than with the direct DjVu conversion.
The new iPad with its high res 2048x1536 display might solve the blurriness issue though. I might get one, so maybe it's time to revisit this conversion utility then