Dave, it's very interesting to see the advanced overclocking features Intel has put into Haswell which you've explained well here. It's then massively frustrating to see that they're all crap overclockers as reported in all the various reviews and articles around the web.
The chip you used for this article was running at 4.6GHz, which I take is the best overclock you could get out of it with complete stability? Well, that's yawn-worthy for the old Sandy Bridges as you know and even on my rig with initially a Zalman flower cooler I was able to briefly run the 2700K stably at 5.5GHz with the fan running flat out and the CPU had more to give. I'd bet that on water this chip could do 5.5GHz 24/7 without any problems.
Such a shame Intel are now tuning their chips for mobile applications and not the likes of us PC enthusiasts. With overclocking limitations like this, I just don't get why Intel designed all these enthusiast features into the chip?