I see what icprncss is saying, and yes, that’s sort of true, the Legacy Shapes are similar in role to the old ‘V2 to V3’ etc figures in allowing us to bridge the generations, even if they do things in a different way. They’re a more complicated solution,. but a much more capable one.
if I apply the V4 and M4 Shapes for Genesis inside of Poser, does that mean I can then apply my Poser installed morphs for Gen 4 to Genesis?
Getting back to the original question, the answer is, not directly. GenX in Studio allows you to convert Gen 4 morphs into Genesis Morphs, and those could then be imported into Poser. With the Gen 3 add-on packs GenX will even convert Gen 3 figures, although you can’t use their textures on Genesis without using Texture Converter 2 to convert them to Gen 4 standard.