[tomsem]

Re sheet music, I haven't had any issues with wavy staff lines, even when there's significant page curl. The software does a very good job of uncurling (uses laser lines to compute geometry). And yes this is all PDF end product (straight out of the CZUR software). For some sheet music books, I'll probably want to go back in and add TOC page links with Acrobat (or whatever I wind up replacing it with) and push the button to reduce file size.

There are at least a couple of GitHub projects that purport to straighten things, not sure how well they work but I've been meaning to check them out.

Fujitsu still makes an overhead scanner for book scanning, and does some sort of straightening. But costs a bit more, and CZUR seems to have more happy customer reviews on average.

I've thought about making a book cradle to help allow the spine to be flatter and help stabilize as I press down to hold pages (there are yellow 'finger cots' to help with this, software removes them from image), but so far I have a few 'chocks' that I put under there and reconfigure as I move through the book. And it is quite fast enough for me.