You might also consider some sort of "Overclock Potential" bar chart. Gabe notes it takes 10C to see a 1.5-2% overclock gain.

If we are seeing at most 9 degrees from best to worst, that's only 1.5%

So if you ran the GT at 4000Mhz, the best block would afford you 4060Mhz??

I think that helps put things into a more bottom line Mhz perspective.

Or if someone currently has a HK and they are thinking of "Upgrading" to the AC Kros....the difference is 2.2 degrees or .38%. 4000MHz-->4015MHz

IMHO, while temperature is something we all THINK we understand because everyone has the ability to measure....I don't think people really understand what temperature means to overclock.

Some sort of simple bar chart showing OVERCLOCK in MHZ would be a good way of speaking a common language to a larger audience.