I've just completed some early testing on V4 to get it to work with SkinVue.  Here are some early observations:

1. The joint configuration is far superior in V4 compared to V3 - much smoother natural looking bending and fewer kinks

2. The material zones and material UV's have all changed. The body material is now a two piece material (Torso and Limbs) with all of the remaining material zones (e.g. arms, hands, feet, neck) tied to these two maps.

3. The eye materials are way different - they offer more flexibility but at a tradeoff of complexity. I'm not so sure that this is a good thing here, but I'm reserving judgement.

4. The morphs are now all self contained in the Cr2 - no more injection files.  I find them to be much easier to use and they seem to offer a pretty good array of cabailities.

5. The skin maps available from Daz (both the standard and high-res versions) are surprisingly average. I think they are going to leave it up to the 3rd party developers of the world to fix this. On the flip side, they do include a reasonably good poser shader with the materials to make up for some of the deficiences.

6. The ability to conform and fit clothing to V4 through the new magnetize pose feature which essentially copies the morphs (deformers) into the clothes is a godsend.  No more Tailor or twiddling morph dials/magnets is required.