I think you have to consider the quality of the various models. Pser 4 has the narrowest range in the box, and the male and female figures, Posette and Dork, have some odd behaviour at knee and elbow joints. Poser 5 figures have largely sorted this. Paser 6 has even more figures. But the Base Vicky 3, Mike 3, and Aiko 3 are all currently free downloads from DAZ 3D, so that's less of an issue than it might be. Does Poser 6 still include the Poser 4 render engine? I agree that it's fast, and you don't need all the fancy stuff for the basic painter's guide approach. (All versions have the traditional jointed-mannequin figure, if that matters.) If your mother wants different faces, there's not really any free options. Maybe a few free figures, but DAZ make the mecessary morphs paid-for extras. DAZ Studio for free and the 3D Starter Content, currently in the Epic Fantasy Sale, looks like a pretty good start. The 3D Starter has the reduced resolution versions of Mike and Vickie, which have a fairly complete set of morphs, and several animals, plus some scenery and props and stuff.