I've read a little about different classes of SD cards. 2, 4, 6, 10. . . My question is, does it really matter? Will a lower class card fail? I've got a class 4 8g card right now. Didn't pay ANY attention to the class when I bought it. I'm gonna grab a 16g, but I'm not sure if I should pay extra for a higher class. I've heard both opinions, that the higher class is worth it and that it didn't really matter unless you're storing videos on it.