[Moonraker]

You can certainly use an Opticbook 3600 scanner for scanning two pages at a time using Abbyy Fine Reader software. The result will be equally good as using an ordinary flatbed scanner.

I am doubtful whether this is possible using Plustek's Book Pilot software that comes with the Opticbook. I believe it can only manage one page at a time.
This is where you need the minimum 6mm gutter on your book because half the book hangs over the side. The scanner beam can not read right up to the edge of the glass but can read 6mm in from the edge..

Also, I don't believe that the Book Pilot software is an OCR programme. I think it will scan your book into images which then have to be sent to an OCR programme such as AFR. I think Plustek bundle AFR 5 with their scanner - which, quite frankly, is not up to the job. You need AFR 7 or 8 for professional results.

The Opticbook scanner surface is about the same size as a regular A4 scanner so it is large enough for the majority of books.

I use AFR with both my scanners. I used Plustek's own software very briefly when I first got the Opticbook. I found it tiresome to use compared with Abbyy FR so I gave up on it.

I am busy using AFR at the moment but later I will try Plustek's software again and report back here.