hi man! Im glad to be of some help!
Well, dont know if there is fPrime for mac, but have you check the new lightwave 10.0? In this Lightwave you have a new thing called VPR ( Viewport Preview Renderer ), its a Open GL render within layout work space, and let you see
like instant feedback of your scene, with ray trace shadows, reflections, radiosity, hdr, Oclusion, everything man! even volumetric light! Its AMAZING! you just have to change in your view, instead of wireframe or texture shaded solid, you change that to VPR, and you will be amaze!
Check this video man:[link]
Im working with lightwave 10, and I can tell you, the vpr its awesome.