Huh.  A little surprised I never got a response. 

Anyway, I went ahead and converted all my Poser custom mag effects to morph targets and bought V6 Infinite.  The MT approach actually works better than the mags, especially when figure twisting or bending moves the mag zones away from where I want the mag effects manifest.  Also, the python scripts for animating the effects run faster than they did with magnets, so it was probably worth doing whether I stayed with P7 or went to V6 for rendering.

But the renders in Vue are spectacular, so I'm glad I moved to Vue.