Comparing the effects of Quad Channel memory performance over Dual Channel memory performance on the Z68 platform is near impossible for the simple fact that we see the new X79 platform crush the Z68 one in certain areas, but you can't deny that most of that is probably due to the performance of the new i7 3960X more so than the memory on offer.

I think the next thing we really need to look at is the performance of Dual Channel on the X79 platform and compare that to Quad Channel performance. Not in the synthetic way we did today, though, instead we need to be looking under more real world situations like CINEBENCH and MediaEspresso to see if the new technology makes a real world difference.

For the moment the best way for us to test the performance of Quad Channel memory is going to be under SiSoft Sandra as it seems to be able to show us the difference between Dual Channel and Quad Channel. The results are also consistent as we can see that when we use Dual Channel on the X79 platform, those numbers line up to those of the Z68 Dual Channel albeit just a little slower.
One of the weirdest things at the moment, though, is the latency for RAM. Same timings, same speed and what would be an overall faster CPU on the X79 platform, sees that RAM latency is slightly worse than its Z68 counterpart.

In the end, though, you can see that when it all comes down to it, the new X79 platform is significantly faster than the Z68 one when comparing it under programs like CINEBENCH and MediaEspresso.
The numbers you're seeing out of other websites, though, when it comes down to Quad Channel performance is something you need to take into consideration, especially if they don't expand their RAM testing outside of AIDA64. I think it's time to see the difference in Dual Channel and Quad Channel performance on the X79 platform in some more real world orientated benchmarks.