Quote - Genesis UV sets have different numbers of vertices. Could you explain the reason behind this, or is in an issue that we can expect to be "fixed" with a consistent number of vertices (and consistent splitting between body part when exported as a .cr2)?

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

Quote -  I ask as this would seem to have some bearing on current/future Poser compatability of Genesis.

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.