This was a test comparing 24fps conform to optical flow.The 60 fps to 24 fps conform using Cinema Tools is about the limit before the footage looks to jerky. With Optical Flow in Apple Motion, shot duration (RAM size?) seems to be the limiting factor. If I go beyond 30%, I get stuttering and artifacting after about 400 frames. I know that you can get better results using simpler back grond and foreground shots. Here is a great tutorial from CrumplePop on using Optical flow: 1000fps for free – using Motion Optical Flow instead of Twixtor
Shot with Lumix GH1 with 28Mbs settings, post in FCP6 and Motion, compressed to 5Mbs with Elgato Turbo h.264HD. No grading.