You would also need proprietary content for any different Poser figure out there. But problem is, not many support them. 

That being said, while I can understand that you prefer V4, and would like to see some of the Genesis content work with her, it might be optimistic to expect content creators to add V4 compatibility to their Genesis clothing options, adding to that that you want it to work in Poser I assume.  As I said, two different rigging methods, different body shapes, and different scaling, make it a lot of work. 

V4 is .. what .. two decades old now?  She was the prime lady for a long time, but there is a "sameness" to so many of the characters for her. I'd rather spend the money on content that uses modern features than trying to make old content work with the new software. That's me, though. 8-)