I too have spent a significant amount of time comparing the processors and find myself with more questions than when I started.
I am looking to build a system for architectural rendering from Maya's Mental Ray and the Maxwell and Vray plug-ins for Rhino. The Phenom II 1090T has good benchmarks on Cinebench only out done by the higher end 6 core Intel's at 3 times the price. I'm also looking at the Opteron 4180 so I can build a multiprocessor system even though they are a slower processor I can get more cores to cut down render times even further, since my understanding is that the Phenom's can t run in a multiprocessor system. Please correct me if I'm wrong I would love to get two in a system and be done with it.
There is a motherboard on Newegg that will run <a href="http://www.newegg.com/Product/...2-203R-_-Product">4
quad-core or 6-core processors</a> but the AMD product page says that the 4000 series can only run two on a board. If I can run 4 of the 4180's that will give me a significant decrease in my render times which will equal more productivity.