I read that the hi resolution mesh of v4 causes problems with bending as a result of the polygons collapsing onto one another. So, while those full resolution figures can be weightmapped, and will work better than the previous joints, they won't work as well as the other figures. 

And, I was probably thinking of the mil three RR figures. It's been ages-but those were my figure of choice for a long time. And, I was hoping to inspire someone else to weight  map them;)