It would definitely be useful. Would make rigging life much easier.

 

I don't see a point in retopo'ing the Gen4 figures, their meshes are pretty decent (if not a bit heavy), but the native poser figure's meshes are horrible and could definitely benefit from a rebuild.

But what about new UV maps?  The new topology would require new maps. Can those also be transferred? 

 

@Ray: The morphs would likely be projected onto the new topology. Its usefulness would show when rigging, as a mesh usually has to be fine-tuned during the rigging process unless you're building a low-res standard mesh with little modeled detail and mostly rows of quads. 

 

~Shane