You have to put the same class MB to compare, that is my point. In the review you can see : Whether or not the better overclocking we've seen with Z97 boards in general - three out of four hit 4.8GHz which only one Z87 board managed - is due to some behind the scenes tweaking in support of the new CPUs is anyone's guess at the moment, but we do have high hopes for the Devil's Canyon, especially with the supposed improved thermal interface between the core and IHS.
So for Gigabyte Z97P D3 vs Z87 D3HP, I said for ocing the z97 is better than the z87 in general. That makes sense.