*I'd like to know the number of items for sale over at CP. There never seems to be a lot of new stuff being released. Maybe I'm wrong about this.
Rendo and Daz both seem to have way more "content" than CP.
Perhaps this is just the market niche that they are happy with; which is fine.

*CP must have more new content than Renderosity, because everything that appears on Renderosity also appears on CP, although I think there may be a 24-hour lag;  on top of the Renderosity material, CP has items from the likes of poserworks, RDNA, PhilC and Vanishing Point.   None of those are exclusive to CP, but CP does do a reasonable job of supporting the Poser 7 figures, plus TY2 and the Mikis.

CP is about E-frontier products, meaning Poser and Shade.   You can find items on there that are for other applications, especially Vue, but I'd hardly expect CP to have much interest in plugging DAZ/Studio, Carrara, or Bryce.   After all, D/S is meant as a direct competitor to Poser.   Carrara has and will have no support for Poser 7.   Bryce should long ago have gone the same way as the practice of painting reindeer on the walls of caves.