I was playing around with a C100, and what better way to test the camera's AVCHD codec then to shoot your girlfriend baking cookies? I think the codec holds up very well. See for yourself.
This is some footage from the Canon C100. It was recorded internally in AVCHD. I shot all the footage at 30p, and then conformed to 24p in FCPX to give the footage a "dreamier" look. I also converted to ProRes422 before editing. Nothing was graded. This is straight out of the camera with the EOS Standard Picture profile "baked in" (pun intended).
The lens used was the Canon 24-70 f/2.8.