I've experienced very good results with virtualization on 16 core bulldozer-era Opteron chips. That is one of those "on-paper" weaknesses that doesn't show up in the real world with typical loads.
Below is my full post. The bolded paragraph address what you are talking about.
If you are going to quote someone; anyone; then try not to edit out information that is pertinent to your response.
The FX-8350 is not a true 8 core CPU.
The CPU is basically made up of 4 modules with 2 core each. Therefore, every two cores shares the same resources such as the Floating Point core and shared L2 cache. If the FP Core or the L2 cache are being heavily used by both CPU cores, then the cores basically have to wait for each other.
Having said that, the "module concept" should offer better performance than Intel's virtual cores using Hyper Threading. If Intel's CPU used a similar concept rather than Hyper Threading, then Intel's CPUs would offer even better multi-core performance.