I never used the flash memory since I directly upload from the camera HD. One this I should mention is that the software cannon includes for transferring video is much faster than using PD to capture the video files. Sometimes PD will get to 100% and then pause and just hang. I typically end up stopping the program.
Cannon's capture program works much better. As for editing, it do not have any problems. Just remember to save often since PD does crash occasionally, but this is not because of the file format.
Jim
Q9300 2.5 GHz
4 GB Ram
Nvidia 9800 GT