I'm a fan of both Asus and ASRock. In the past couple years ASRock has vastly improved the quality of their hardware and components used. Other than price point and feature mix its getting harder to distinguish between the two. Ironically our build plans are very similar. I was also going after the Z68 chipset for the same reasons you indicated.
My short list even included the same two Mobos... but I've since narrowed it down to the Z68 Professional Gen3. As much as I like the look and specs of the Extreme4 Gen3 I couldn't consider it unless a solution is found to the
ASRock Z68 Extreme 4 Clock Interrupt BSOD problem I'll admit it's disappointing to read that even with all the thousands of end users around the world, reporting the same problem, in multiple forums, that ASRock is standing firm saying they have been unable to reproduce the problem in their labs and claiming it must be an user error (a hardware config problem/bad memory/BIOS settings etc) With so many end users having the same problem, even if ASRock can't reproduce it they should at least admit there must some kind of problem and they will continue to investigate it until its resolved.
FYI: As you probably know the NH-D14 CPU cooler is quite large. I already have mine.
If you don't plan on buying a new case just make sure your current case is wide enough to accept it. Many users find the cooler is so tall they can't use it in their case with a case "side" fan. I have a HAF 922 and it fits just fine but the 922 is also 10" wide. You'll be fine with the G.Skill Ripjaws. They fit under the cooler with 1/4 inch clearance whereas the cooling fins on some memory like Corsair are too high and have to be cut down.