WHY you're still using V4 when there are other viable figures available for use in Poser.

Because Poser doesn't put figures behind an abstraction layer so every new figure has to have comparable poses, expressions, clothing and hair fits provided for it to gain traction. Because newer figures have lower head poly counts or unusually divided head geometries which can be headaches for a morph artist (separated jaw in Dawn, unseparated mouth in Scarlet).

Because the makers of those figures don't always constructively market how they leverage modern Poser's rigging capabilities.

Because the figures might not come with the equivalent of Morphs++ which by now is IMO a basic standard. 

Because V4 was sculpted by medical illustrators using human models as references which means most of her proportions aren't uncanny (not implying the others are uncanny).