Based on some dA forum conversations, I think the idea with the lower poly count is DAZ wants to push partner artists to use maps for more, which I think is the direction the industry has gone. Which is also why the UVs are split over more maps. Better zBrush integration, more map surface for texturing, including displacement/normals.
Yeah, that's got to be one of the ideas behind it. The central idea is probably that they want to reduce the load on the CPU so their software runs faster. In general, it's probably best to use as few polygons as you can get away with. In my specific case, I often enlarge certain areas to the point where I have to choose between smoothing and shape control because the polygons have become too large. Displacement maps are probably the simplest solution, at least for breasts. A geograft or set of HD morphs may be a better solution for the hip area. Tests have shown me that bending the leg-hip joint can really mess up a displacement map. I tried that with g2f though. The better weight mapping in g3f may make that easier.
As I think about it more, I'm warming up to g3f. I'll probably pick up the new Vickie this weekend.