The Daz help pages say that you do not need to re-install the Genesis starter essentials but need to re-install the Genesis starter essentials for Poser, and the DSON for Poser plug in. 

 

The Essentials item are two different things two different items.  But if you do not use Poser, then of course you don't need to re-install the items for Poser.

 

I did the DS 4 to 4.5 upgrade just a few days ago, so that's all I know.  As for content, I have that installed in a custome location without uninstallation options, so I don'think I need to re-install those.

 

I can't say for plug-ins, but when you launch DS4.5, it will check and update you on those.

Eternal Hobbyist