Of course, I will not only use the device as an ebook reader; I use google services such as gmail, voice input or Chromecast. For this reason alone, a more current OS is an advantage. Features such as split screen mode, night mode are only available in later versions. Improved Bluetooth, power management and security as mentioned earlier. Just look for the version differences and decide whether you need it.
https://de.wikipedia.org/wiki/Liste_...roid-Versionen