Interesting, I did not see that big a difference between the 2, and I shot them in identical conditions side by side on the same events.
ISO 800 is pretty close IMO, and even above that. I saw a bigger difference in sharpness due to the weaker AA/larger sensor. I have shot them both in many sporting events and marching band competitions. I find them to be within 1-1.5 stops of each other. I would love to be able to use 25600 cleanly, thus why I eagerly wait to see what the 1DX brings. (ISO 25600 from the 1D4 at the bottom, good for web sized images)
ISO 6400 sports w/7D
ISO 12800 on the 1D4
Nice comparison Teeamspeed.Used properly you can get very useable ISO 12,800 shots out of the 7D.While I don't really like any camera's OOC
j-pegs The 7D can produce some pretty awesome RAW generated shots.