The option removes one of the penalties of creating composites for the booklist that show notes when the user hovers over the column. Risks: near zero. Nothing changes unless the option is changed from its default. If the option is changed then there is a risk that in some context the option will be ignored, resulting in the same behavior as before. Take 2 notes: You are correct about the if. I had managed to corrupt my test data so I didn't see that the values for all non-composite columns were being emptied.
calibre

calibre is an e-book manager. It can view, convert, edit and catalog e-books in all of the major e-book formats. It can also talk to e-book reader devices. It can go out to the internet and fetch metadata for your books. It can download newspapers and convert them into e-books for convenient reading. It is cross platform, running on Linux, Windows and macOS.
For more information, see the calibre About page.
Screenshots
Usage
See the User Manual.
Development
Setting up a development environment for calibre.
A tarball of the source code for the current calibre release.
Bugs
Bug reports and feature requests should be made in the calibre bug tracker at Launchpad. GitHub is only used for code hosting and pull requests.
Support calibre
calibre is a result of the efforts of many volunteers from all over the world. If you find it useful, please consider contributing to support its development. Donate to support calibre development.
Building calibre binaries
See Build instructions for instructions on how to build the calibre binaries and installers for all the platforms calibre supports.