Quote - That is the whole point of having multiple UVs is it not?

No, it's not, necessarily. And they don't seem to be the cause for this disparity AFAICS. The differences aren't well understood, seem odd, and makes supporting swapping UV Sets in Poser harder.

Quote - I usually want to have two UV sets when an object is to be viewed from e.g. from behind and from the front. So i want to have one UV with it's seams on the backside and one with the seams on the front. Those would necessarily have a different number of vertices.

Genesis V4 and Genesis M4 don't have UV sets that have splits "out of sight" on the back for V4 and the front for M4. And the group splits are the same between the different morphs becuase, well, they're morphs... so I'm really not convinced that the uv sets really need different seams to that degree. I'd love to see where the differences actually are though, if that's the issue.

Quote - > Quote - I'm a bit puzzled actually as to why Genesis has a grouped mesh in Poser - doesnt' Poser support "single skin" meshes like DAZ 4 does? (honest enquiry, I thought Poser 9/2012 were supposed to suppor tthis feature and was surprised to find Genesis all split up).

It does, but that does not mean you want it that way. In Poser (as in DS) you can select a body part by directly clicking with your mouse in the 3d-viewport (besides selecting the body part in the actors list menu). But the 3d-viewport does not show actors, it shows only the mesh. So when you want to get the 'head'-actor selected when you click on the mesh-part that supposedly belongs to the head, Poser has somehow to know which actor belongs to that mesh part and for this it uses the groups.

Ah! Thanks for that. I had assumed that if Poser had support for a single-skin mesh then that would include the ability to select the actors. I'm not sure how much use it would be to have a figure where selecting joints is difficult to impossible, so yes - grouping Genesis in Poser makes perfect sense in that light.