I bought the Canon S100 about 10 months ago and shortly after that I bought the Mr. Flash 128MB CF card from Newegg. So far, everything has been working great under moderate usage. My experience with the 128MB CF card is that works with pretty good speed for the first 100 or so photos(estimate), but slows down considerably after that. The slowdown is noticable when powering up the camera (the green light flashes for quite a while), and during the storage period after snapping a photo. This can be irritating but, for me, is just a slight inconvenience. I imagine it also wears the battery down a bit faster, but I really couldn't tell without more testing. At the default setting, I can get about 209 photos on it. Of course, I don't see this behavior with the 8MB card that came with the camera. I haven't tried any other high capacity CF cards at this point, so I can't give a comparison with "faster" units.