My motherboard is Windows 8 certified and my USB keyboard works perfectly fine during boot. Additionally you can get Windows 8 to give you more boot options if you just keep rebooting while it is trying to start up. Eventually it will give up and attempt to repair your computer before asking what you want to do next.
Has anyone experienced the problems described in the article actually in practice or is the article purely theoretical?
The requirements only apply to systems that are Windows 8 certified, not individual components. If you built your system then it may support Fast Boot but not have it enabled out of the box. Motherboard manufacturers are unlikely to turn it on by default because it requires you to have a graphics card with a UEFI option ROM rather than a traditional VGA BIOS, and there's something of a chicken and egg problem in turning it off if you're using an older card.
Has anyone experienced the problems described in the article actually in practice or is the article purely theoretical?