Now consider whether Folding@home uses multiple CPU's (multi-threads) or single-threads one task.
Then consider whether the additional 41W TDP of the FX-8350 is worth that marginal increase in multi-tasking performance.
Finally, I added the higher-end Intel CPU that has a substantial increase in performance (and price) for the same TDP - at least if you buy the high-end Intel it gets you substantial performance improvement for that price. it'd be a much smarter long-term investment of your money to spend it in calculations rather than in energy costs that you them have to cool away again.
I'll also leave you with a question: I thought many of these distributed computing projects now allows exploiting GPUs? If so that may be a much more viable option.