I tend to agree with you, but if you want to spend the money on a used but tested and working E6700 to squeeze all you can out of the processor, it might be worth it. Depending on how cheap you can get one.
I have compared your processor and the E6700 side by side.
The advantages of the E6700...500 MHz faster, and twice the L2 cache size (4 MB).
http://ark.intel.com/compare/27251,27249
I see the E6700 going for $40 - $60 on eBay, buy it now.
You will have to decide if that performance increase is worth ~50 bucks to you or not.