[Quoth]

The My Books can fill the screen with the equivalent of the top row of Home (grid view mode), more flexibly. The rest of the Home Screen is either pointless or easily accessed content via My Books settings.

You only lose the adverts on the Home with SideloadedMode=true.

Try it. One click in Settings, Account will revert to having Home, My Books & Discover, without losing any reading settings or ebooks on the device, if you are logged in on your account when you add SideloadedMode=true. It sets it to false and keeps the setting text.