I don't have a spreadsheet! Honest! Moose are crap at numbers! If this were the case Moose would not be crashing into cars from a height but just wafting down gently.
Regarding the HD6870 1GB so far it does not seem to be such a great overclocker relative to the HD6850 1GB. If you can get around 100MHZ on the core it is decent. Perhaps when the non-reference versions are launched better overclocks will be achieved.