You'll find that DAZ figures, Posette & Dork, and Poser figures from around P7 onwords are all single mesh figures. The problem most have is that many of the modelling programs can't handle the single mesh grouping (AKA 'soft split') they use, on loading they split the mesh along the group seams giving you a multi mesh figure (AKA 'hard split'). Some programs can handle it, you also have UVMapper (pro or classic) which will weld the multi mesh back into one mesh and keep the grouping.

As for V3, you get the same in DS4, converting old style rigging doesn't work very well, you need to spend time adjusting the bones & the weight map to get it to work half decent.