I am still looking at Carrara too. I hope that Evoia will add symmeterical modeling plug in for Carrara's modeling room to make it a complete and useful application. I would hate to wait for the next version for this essential modeling tool. In my opinion Carrara is one step closer to high-end with the big boys. Carrara's renderer is very impressive and fast. I don't know very much about the Mental-Ray but I heard that it is the only true photon renderer engine with most of calculations that existed for 3D application. I wouldn't look into MentalRay because I think I am happy with Carrara's renderer for my project.