I would say Very usable 6400 iso files from what you posted. How much or did you have to clean them? To be honest, Im also very reluctant to crank it past 3200 unless i absolutly have to. Probably more of a mental block than anything else, but we did this weekend. Im going through stuff now but the files @6400 were on the 5dII. My wife uses the 7D and she sets it where i Suggest. My problem lies where i dont have the opportunity to put a flash on the camera with the higher iso settings. Ill shoot the 7d all day long at 3200 iso, especially when i can get a flash into the mix. But the ceremony yesterday was a catholic wedding, no flash during the ceremony. So on the 7d we put it in av mode, plus 2/3, and fired away. I was afraid to push it any further,,again probably a mental block on my part. Not so with the 5dII. Files at 4000 iso, with the 70-200, were very very usable I would think that the 1DmkIV could shoot w/o a flash @6400 all day long and ive been told 8000 (think thats right) is also clean. Need to get my hands on one or im hoping one of the guys that has one can post some examples. I really like what im reading and seeing. I probably should have handed my wife the 5dII and experimented with the 7d a bit, but i just didnt think of it.