subD and dead horse beating - 

REYES is a render engine type, subD is a surface type so I understand that they are not the same thing but can be used together. 

So you can subdivide a low poly cube in Poser as input and render a sphere as output? That is what subDs do, n'est pas? More important, you can subdivide a subD face for localized increased level of detail, take one of these new faces and increase detail and so on, so that your Level 0 is your base mesh, your Level 1 has some arbitrary detail, your Level 2 has arbitrary detail riding atop your Level 1 and so on.

So again, is the resultant mesh really a subD or is it a smoothed / normal interpolated poly mesh? Sorry if my tone seems harsh; it's not meant to be.