Class 4 cards are rated at 4MB/s min (of course). That's 32Mb/s. So with a HF100 that has a 17Mb/s rate is there any reason to get a Class 6 card over a Class 4? Most posts I read people are buying Class 6. When you get into 16GB sizes, the cost can be quite a bit: currently Sandisk Extreme III (class 6) is ~$160 vs $65 for the class 4 version (Ultra II or HD Video) Patriot, A-Data and Transcend are all going for half what Sandisk is, but the I've read more failure issues than with Sandisk. I don't wan to skimp only to have data lost. I've only ever used Sandisk and had great luck. Any hands on experience with others?