"It looks like Genesis 8 is a minor update of Genesis 3 and that is why the Updater worked."

This is misleading and relates to Genesis 8/ Genesis 3 when either are ported across to Poser only. In truth, when porting to Poser much of the original functionality of the latest Daz 3D figures are lost. And your comment speaks more about the porting process itself, than the actual figure capabilities.

The vast majority of improvements with Genesis 8 are strangely focused on usage within Daz Studio which is the platform the figure is designed for.

Some of Genesis 8 new features.

Better expression control with Powerpose - link to vid here

New Eyelash setup

Switched to A pose for better shoulder realism when posing

Fantastic New Skin shaders

Muscle Flexions and improved rigging

Mesh improvements and refinement