OK I downloaded the trial version of FineReader and I'm impressed. Even with slightly uneven lighting and no sheet of glass to flatten things out it did impressively well. On the book page I tried the only "error" was font sizing on a word in italics. It even managed a page from "The Lorax" with mostly extra non-text recognised, with that removed it was fine. Magazines not so well, lots of extra spaces in the middle of words although it did pretty well on the slanted fragment of the opposing page.
Thank you so much for your extensive reports and evaluations, ereszet, this is wonderfully useful stuff.
Overall, it's enough for me to ask for a refund on my as-yet undelivered A3 scanner and start shopping for a couple of sheets of glass. I think I'll be using my camera for this stuff. camera and schoolchildren, possibly, if I can persuade a friend that her desire for money matches my low wage offer
Edit: glass is cheap... 3 sheets (paperback, trade paperback and A3) cost me ~$30 including having the edges polished so they're not sharp. Given the labour costs the actual glass has to be just about free.